# less

## NAME



           less - display the contents of a file in a terminal
    


## SYNOPSIS



           **less -?**
           **less --help**
           **less -V**
           **less --version**
           **less [-[+]aABcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]**
                **[-b** _space_**] [-h** _lines_**] [-j** _line_**] [-k** _keyfile_**]**
                **[-{oO}**_logfile_**] [-p** _pattern_**] [-P** _prompt_**] [-t** _tag_**]**
                **[-T** _tagsfile_**] [-x** _tab_**,...] [-y** _lines_**] [-[z]**_lines_**]**
                **[-#**_shift_**] [+[+]**_cmd_**] [--] [**_filename_**]...**
           (See the OPTIONS section for alternate option syntax with long
           option names.)
    


## DESCRIPTION



           **Less** is a program similar to more(1), but it has many more
           features.  **Less** does not have to read the entire input file before
           starting, so with large input files it starts up faster than text
           editors like **vi**(1).  **Less** uses termcap (or terminfo on some
           systems), so it can run on a variety of terminals.  There is even
           limited support for hardcopy terminals.  (On a hardcopy terminal,
           lines which should be printed at the top of the screen are
           prefixed with a caret.)
    


## COMMANDS



           Commands are based on both **more** and **vi**.  Commands may be preceded
           by a decimal number, called N in the descriptions below.  The
           number is used by some commands, as indicated.
    
           In the following descriptions, ^X means control-X.  ESC stands for
           the ESCAPE key; for example ESC-v means the two character sequence
           "ESCAPE", then "v".
    
           h or H Help: display a summary of these commands.  If you forget
                  all the other commands, remember this one.
    
           SPACE or ^V or f or ^F
                  Scroll forward N lines, default one window (see option -z
                  below).  If N is more than the screen size, only the final
                  screenful is displayed.  Warning: some systems use ^V as a
                  special literalization character.
    
           z      Like SPACE, but if N is specified, it becomes the new
                  window size.
    
           ENTER or RETURN or ^N or e or ^E or j or ^J
                  Scroll forward N lines, default 1.  The entire N lines are
                  displayed, even if N is more than the screen size.
    
           d or ^D
                  Scroll forward N lines, default one half of the screen
                  size.  If N is specified, it becomes the new default for
                  subsequent d and u commands.
    
           b or ^B or ESC-v
                  Scroll backward N lines, default one window (see option -z
                  below).  If N is more than the screen size, only the final
                  screenful is displayed.
    
           w      Like ESC-v, but if N is specified, it becomes the new
                  window size.
    
           y or ^Y or ^P or k or ^K
                  Scroll backward N lines, default 1.  The entire N lines are
                  displayed, even if N is more than the screen size.
                  Warning: some systems use ^Y as a special job control
                  character.
    
           u or ^U
                  Scroll backward N lines, default one half of the screen
                  size.  If N is specified, it becomes the new default for
                  subsequent d and u commands.
    
           J      Like j, but continues to scroll beyond the end of the file.
    
           K or Y Like k, but continues to scroll beyond the beginning of the
                  file.
    
           ESC-SPACE
                  Like SPACE, but scrolls a full screenful, even if it
                  reaches the end of the file.
    
           ESC-b  Like b, but scrolls a full screenful, even if it reaches
                  the beginning of the file.
    
           ESC-j  Scroll forward N file lines, default 1.  A file line is a
                  complete line in the file, terminated by a newline.
    
           ESC-k  Scroll backwards N file lines, default 1.
    
           ESC-) or RIGHTARROW
                  Scroll horizontally right N characters, default half the
                  screen width (see the -# option).  If a number N is
                  specified, it becomes the default for future RIGHTARROW and
                  LEFTARROW commands.  While the text is scrolled, it acts as
                  though the -S option (chop lines) were in effect.
    
           ESC-( or LEFTARROW
                  Scroll horizontally left N characters, default half the
                  screen width (see the -# option).  If a number N is
                  specified, it becomes the default for future RIGHTARROW and
                  LEFTARROW commands.
    
           ESC-} or ^RIGHTARROW
                  Scroll horizontally right to show the end of the longest
                  displayed line.
    
           ESC-{ or ^LEFTARROW
                  Scroll horizontally left back to the first column.
    
           r or ^R or ^L
                  Repaint the screen.
    
           R      Repaint the screen, discarding any buffered input.  That
                  is, reload the current file.  Useful if the file is
                  changing while it is being viewed.
    
           F      Scroll forward, and keep trying to read when the end of
                  file is reached.  Normally this command would be used when
                  already at the end of the file.  It is a way to monitor the
                  tail of a file which is growing while it is being viewed.
                  (The behavior is similar to the "tail -f" command.)  To
                  stop waiting for more data, enter the interrupt character
                  (usually ^C).  On systems which support poll(2) you can
                  also use ^X or the character specified by the --intr
                  option.  If the input is a pipe and the --exit-follow-on-
                  close option is in effect, **less** will automatically stop
                  waiting for data when the input side of the pipe is closed.
    
           ESC-F  Like F, but as soon as a line is found which matches the
                  last search pattern, the terminal bell is rung and forward
                  scrolling stops.
    
           g or < or ESC-<
                  Go to line N in the file, default 1 (beginning of file).
                  (Warning: this may be slow if N is large.)
    
           G or > or ESC->
                  Go to line N in the file, default the end of the file.
                  (Warning: this may be slow if N is large, or if N is not
                  specified and standard input, rather than a file, is being
                  read.)
    
           ESC-G  Same as G, except if no number N is specified and the input
                  is standard input, goes to the last line which is currently
                  buffered.
    
           p or % Go to a position N percent into the file.  N should be
                  between 0 and 100, and may contain a decimal point.
    
           P      Go to the line containing byte offset N in the file.
    
           {      If a left curly bracket appears in the top line displayed
                  on the screen, the { command will go to the matching right
                  curly bracket.  The matching right curly bracket is
                  positioned on the bottom line of the screen.  If there is
                  more than one left curly bracket on the top line, a number
                  N may be used to specify the N-th bracket on the line.
    
           }      If a right curly bracket appears in the bottom line
                  displayed on the screen, the } command will go to the
                  matching left curly bracket.  The matching left curly
                  bracket is positioned on the top line of the screen.  If
                  there is more than one right curly bracket on the bottom
                  line, a number N may be used to specify the N-th bracket on
                  the line.
    
           (      Like {, but applies to parentheses rather than curly
                  brackets.
    
           )      Like }, but applies to parentheses rather than curly
                  brackets.
    
           [      Like {, but applies to square brackets rather than curly
                  brackets.
    
           ]      Like }, but applies to square brackets rather than curly
                  brackets.
    
           ESC-^F Followed by two characters, acts like {, but uses the two
                  characters as open and close brackets, respectively.  For
                  example, "ESC ^F < >" could be used to go forward to the >
                  which matches the < in the top displayed line.
    
           ESC-^B Followed by two characters, acts like }, but uses the two
                  characters as open and close brackets, respectively.  For
                  example, "ESC ^B < >" could be used to go backward to the <
                  which matches the > in the bottom displayed line.
    
           m      Followed by any lowercase or uppercase letter, marks the
                  first displayed line with that letter.  If the status
                  column is enabled via the -J option, the status column
                  shows the marked line.
    
           M      Acts like m, except the last displayed line is marked
                  rather than the first displayed line.
    
           '      (Single quote.)  Followed by any lowercase or uppercase
                  letter, returns to the position which was previously marked
                  with that letter.  Followed by another single quote,
                  returns to the position at which the last "large" movement
                  command was executed.  Followed by a ^ or $, jumps to the
                  beginning or end of the file respectively.  Marks are
                  preserved when a new file is examined, so the ' command can
                  be used to switch between input files.
    
           ^X^X   Same as single quote.
    
           ESC-m  Followed by any lowercase or uppercase letter, clears the
                  mark identified by that letter.
    
           /pattern
                  Search forward in the file for the N-th line containing the
                  pattern.  N defaults to 1.  The pattern is a regular
                  expression, as recognized by the regular expression library
                  supplied by your system.  By default, searching is case-
                  sensitive (uppercase and lowercase are considered
                  different); the -i option can be used to change this.  The
                  search starts at the first line displayed (but see the -a
                  and -j options, which change this).
    
                  Certain characters are special if entered at the beginning
                  of the pattern; they modify the type of search rather than
                  become part of the pattern:
    
                  ^N or !
                         Search for lines which do NOT match the pattern.
    
                  ^E or *
                         Search multiple files.  That is, if the search
                         reaches the END of the current file without finding
                         a match, the search continues in the next file in
                         the command line list.
    
                  ^F or @
                         Begin the search at the first line of the FIRST file
                         in the command line list, regardless of what is
                         currently displayed on the screen or the settings of
                         the -a or -j options.
    
                  ^K     Highlight any text which matches the pattern on the
                         current screen, but don't move to the first match
                         (KEEP current position).
    
                  ^R     Don't interpret regular expression metacharacters;
                         that is, do a simple textual comparison.
    
                  ^S     Followed by a digit N between 1 and 5.  Only text
                         which has a non-empty match for the N-th
                         parenthesized SUB-PATTERN will be considered to
                         match the pattern.  For example, searching for
                         "(abc)|(def)" modified with ^S1 would search for
                         instances of "abc", but would highlight instances of
                         both "abc" and "def".  (Supported only if **less** is
                         built with one of the regular expression libraries
                         **posix** , **pcre** , or **pcre2**.)  Multiple ^S modifiers can
                         be specified, to match more than one sub-pattern.
    
                  ^W     WRAP around the current file.  That is, if the
                         search reaches the end of the current file without
                         finding a match, the search continues from the first
                         line of the current file up to the line where it
                         started.  If the ^W modifier is set, the ^E modifier
                         is ignored.
    
                  ^L     The next character is taken literally; that is, it
                         becomes part of the pattern even if it is one of the
                         above search modifier characters.
    
           ?pattern
                  Search backward in the file for the N-th line containing
                  the pattern.  The search starts at the last line displayed
                  (but see the -a and -j options, which change this).
    
                  Certain characters are special as in the / command:
    
                  ^N or !
                         Search for lines which do NOT match the pattern.
    
                  ^E or *
                         Search multiple files.  That is, if the search
                         reaches the beginning of the current file without
                         finding a match, the search continues in the
                         previous file in the command line list.
    
                  ^F or @
                         Begin the search at the last line of the last file
                         in the command line list, regardless of what is
                         currently displayed on the screen or the settings of
                         the -a or -j options.
    
                  ^K     As in forward searches.
    
                  ^R     As in forward searches.
    
                  ^S     As in forward searches.
    
                  ^W     WRAP around the current file.  That is, if the
                         search reaches the beginning of the current file
                         without finding a match, the search continues from
                         the last line of the current file up to the line
                         where it started.
    
                  ^L     As in forward searches.
    
           ESC-/pattern
                  Same as "/*".
    
           ESC-?pattern
                  Same as "?*".
    
           n      Repeat previous search, for N-th line containing the last
                  pattern.  If the previous search was modified by ^N, the
                  search is made for the N-th line NOT containing the
                  pattern.  If the previous search was modified by ^E, the
                  search continues in the next (or previous) file if not
                  satisfied in the current file.  If the previous search was
                  modified by ^R, the search is done without using regular
                  expressions.  If the previous search was modified by ^W,
                  the search wraps at the end (or beginning) of the file.
                  There is no effect if the previous search was modified by
                  ^F or ^K.
    
           N      Repeat previous search, but in the reverse direction.
    
           ESC-n  Repeat previous search, but crossing file boundaries.  The
                  effect is as if the previous search were modified by *.
    
           ESC-N  Repeat previous search, but in the reverse direction and
                  crossing file boundaries.
    
           ESC-u  Undo search highlighting.  Turn off highlighting of strings
                  matching the current search pattern.  If highlighting is
                  already off because of a previous ESC-u command, turn
                  highlighting back on.  Any search command will also turn
                  highlighting back on.  (Highlighting can also be disabled
                  by toggling the -G option; in that case search commands do
                  not turn highlighting back on.)
    
           ESC-U  Like ESC-u but also clears the saved search pattern.  If
                  the status column is enabled via the -J option, this clears
                  all search matches marked in the status column.
    
           &pattern
                  Display only lines which match the pattern; lines which do
                  not match the pattern are not displayed.  If pattern is
                  empty (if you type & immediately followed by ENTER), any
                  filtering is turned off, and all lines are displayed.
                  While filtering is in effect, an ampersand is displayed at
                  the beginning of the prompt, as a reminder that some lines
                  in the file may be hidden.  Multiple & commands may be
                  entered, in which case only lines which match all of the
                  patterns will be displayed.
    
                  Certain characters are special as in the / command:
    
                  ^N or !
                         Display only lines which do NOT match the pattern.
    
                  ^R     Don't interpret regular expression metacharacters;
                         that is, do a simple textual comparison.
    
           :e [filename]
                  Examine a new file.  If the filename is missing, the
                  "current" file (see the :n and :p commands below) from the
                  list of files in the command line is re-examined.  A
                  percent sign (%) in the filename is replaced by the name of
                  the current file.  A pound sign (#) is replaced by the name
                  of the previously examined file.  However, two consecutive
                  percent signs are simply replaced with a single percent
                  sign.  This allows you to enter a filename that contains a
                  percent sign in the name.  Similarly, two consecutive pound
                  signs are replaced with a single pound sign.  The filename
                  is inserted into the command line list of files so that it
                  can be seen by subsequent :n and :p commands.  If the
                  filename consists of several files, they are all inserted
                  into the list of files and the first one is examined.  If
                  the filename contains one or more spaces, the entire
                  filename should be enclosed in double quotes (also see the
                  -" option).
    
           ^X^V or E
                  Same as :e.  Warning: some systems use ^V as a special
                  literalization character.  On such systems, you may not be
                  able to use ^V.
    
           :n     Examine the next file (from the list of files given in the
                  command line).  If a number N is specified, the N-th next
                  file is examined.
    
           :p     Examine the previous file in the command line list.  If a
                  number N is specified, the N-th previous file is examined.
    
           :x     Examine the first file in the command line list.  If a
                  number N is specified, the N-th file in the list is
                  examined.
    
           :d     Remove the current file from the list of files.
    
           t      Go to the next tag, if there were more than one matches for
                  the current tag.  See the -t option for more details about
                  tags.
    
           T      Go to the previous tag, if there were more than one matches
                  for the current tag.
    
           ^O^N or ^On
                  Search forward in the file for the N-th next OSC 8
                  hyperlink.
    
           ^O^P or ^Op
                  Search backward in the file for the N-th previous OSC 8
                  hyperlink.
    
           ^O^L or ^Ol
                  Jump to the currently selected OSC 8 hyperlink.
    
           = or ^G or :f
                  Prints some information about the file being viewed,
                  including its name and the line number and byte offset of
                  the bottom line being displayed.  If possible, it also
                  prints the length of the file, the number of lines in the
                  file and the percent of the file above the last displayed
                  line.
    
           -      Followed by one of the command line option letters (see
                  OPTIONS below), this will change the setting of that option
                  and print a message describing the new setting.  If a ^P
                  (CONTROL-P) is entered immediately after the dash, the
                  setting of the option is changed but no message is printed.
                  If the option letter has a numeric value (such as -b or
                  -h), or a string value (such as -P or -t), a new value may
                  be entered after the option letter.  If no new value is
                  entered, a message describing the current setting is
                  printed and nothing is changed.
    
           --     Like the - command, but takes a long option name (see
                  OPTIONS below) rather than a single option letter.  Press
                  ENTER or RETURN after typing the option name to change it.
                  You can enter just the beginning of an option name, then
                  press TAB to find all option names which begin with that
                  string.  A ^P immediately after the second dash suppresses
                  printing of a message describing the new setting, as in the
                  - command.
    
           -+     Followed by one of the command line option letters this
                  will reset the option to its default setting and print a
                  message describing the new setting.  (The "-+_X_ " command
                  does the same thing as "-+_X_ " on the command line.)  This
                  does not work for string-valued options.
    
           --+    Like the -+ command, but takes a long option name rather
                  than a single option letter.
    
           -!     Followed by one of the command line option letters, this
                  will reset the option to the "opposite" of its default
                  setting and print a message describing the new setting.
                  This does not work for numeric or string-valued options.
    
           --!    Like the -! command, but takes a long option name rather
                  than a single option letter.
    
           _      (Underscore.)  Followed by one of the command line option
                  letters, this will print a message describing the current
                  setting of that option.  The setting of the option is not
                  changed.
    
           __     (Double underscore.)  Like the _ (underscore) command, but
                  takes a long option name rather than a single option
                  letter.  You must press ENTER or RETURN after typing the
                  option name.
    
           +cmd   Causes the specified cmd to be executed each time a new
                  file is examined.  For example, +G causes **less** to initially
                  display each file starting at the end rather than the
                  beginning.
    
           V      Prints the version number of **less** being run.
    
           q or Q or :q or :Q or ZZ
                  Exits **less**.
    
           The following seven commands may or may not be valid, depending on
           your particular installation.
    
           v      Invokes an editor to edit the current file being viewed.
                  The editor is taken from the environment variable VISUAL if
                  defined, or EDITOR if VISUAL is not defined, or defaults to
                  "vi" if neither VISUAL nor EDITOR is defined.  See also the
                  discussion of LESSEDIT under the section on PROMPTS below.
    
           ! shell-command
                  Invokes a shell to run the shell-command given.  A percent
                  sign (%) in the command is replaced by the name of the
                  current file.  A pound sign (#) is replaced by the name of
                  the previously examined file.  "!!" repeats the last shell
                  command.  "!" with no shell command invokes an interactive
                  shell.  If a ^P (CONTROL-P) is entered immediately after
                  the !, no "done" message is printed after the shell command
                  is executed.  On Unix systems, the shell is taken from the
                  environment variable SHELL, or defaults to "sh".  On MS-
                  DOS, Windows, and OS/2 systems, the shell is the normal
                  command processor.
    
           # shell-command
                  Similar to the "!" command, except that the command is
                  expanded in the same way as prompt strings.  For example,
                  the name of the current file would be given as "%f".
    
           | <m> shell-command
                  <m> represents any mark letter.  Pipes a section of the
                  input file to the given shell command.  The section of the
                  file to be piped is between the position marked by the
                  letter and the current screen.  The entire current screen
                  is included, regardless of whether the marked position is
                  before or after the current screen.  <m> may also be ^ or $
                  to indicate beginning or end of file respectively.  If <m>
                  is . or newline, the current screen is piped.  If a ^P
                  (CONTROL-P) is entered immediately after the mark letter,
                  no "done" message is printed after the shell command is
                  executed.
    
           s filename
                  Save the input to a file.  This works only if the input is
                  a pipe, not an ordinary file.
    
           ^O^O
                  Run a shell command to open the URI in the current OSC 8
                  hyperlink, selected by a previous ^O^N or ^O^P command.  To
                  find the shell command, the environment variable named
                  "LESS_OSC8_xxx" is read, where "xxx" is the scheme from the
                  URI (the part before the first colon), or is empty if there
                  is no colon in the URI.  The value of the environment
                  variable is then expanded in the same way as prompt strings
                  (in particular, any instance of "%o" is replaced with the
                  URI) to produce an OSC 8 "handler" shell command.  The
                  standard output from the handler is an "opener" shell
                  command which is then executed to open the URI.
    
                  There are two special cases:
    
                         1.     If the URI begins with "#", the remainder of
                                the URI is taken to be the value of the id
                                parameter in another OSC 8 link in the same
                                file, and ^O^O will simply jump to that link.
    
                         2.     If the opener begins with the characters ":e"
                                followed by whitespace and a filename, then
                                instead of running the opener as a shell
                                command, the specified filename is opened in
                                the current instance of **less**.
    
                  In a simple case where the opener accepts the complete URI
                  as a command line parameter, the handler may be as simple
                  as
    
                  echo mybrowser '%o'
    
                  In other cases, the URI may need to be modified, so the
                  handler may have to do some manipulation of the %o value.
    
                  If the LESS_OSC8_xxx variable is not set, the variable
                  LESS_OSC8_ANY is tried.  If neither LESS_OSC8_xxx nor
                  LESS_OSC8_ANY is set, links using the "xxx" scheme cannot
                  be opened.  However, there are default handlers for the
                  schemes "man" (used when LESS_OSC8_man is not set) and
                  "file" (used when LESS_OSC8_file is not set), which should
                  work on systems which provide the sed(1) command and a
                  shell with syntax compatible with the Bourne shell **sh**(1).
                  If you use LESS_OSC8_ANY to override LESS_OSC8_file, you
                  must set LESS_OSC8_file to "-" to indicate that the default
                  value should not be used, and likewise for LESS_OSC8_man.
    
                  The URI passed to an OSC8 handler via %o is guaranteed not
                  to contain any single quote or double quote characters, but
                  it may contain any other shell metacharacters such as
                  semicolons, dollar signs, ampersands, etc.  The handler
                  should take care to appropriately quote parameters in the
                  opener command, to prevent execution of unintended shell
                  commands in the case of opening a URI which contains shell
                  metacharacters.  Also, since the handler command is
                  expanded like a command prompt, any metacharacters
                  interpreted by prompt expansion (such as percent, dot,
                  colon, backslash, etc.) must be escaped with a backslash
                  (see the PROMPTS section for details).
    
           ^X     When the "Waiting for data" message is displayed, such as
                  while in the F command, pressing ^X will stop **less** from
                  waiting and return to a prompt.  This may cause **less** to
                  think that the file ends at the current position, so it may
                  be necessary to use the R or F command to see more data.
                  The --intr option can be used to specify a different
                  character to use instead of ^X.  This command works only on
                  systems that support the poll(2) function.  On systems
                  without poll(2), the interrupt character (usually ^C) can
                  be used instead.
    


## OPTIONS



           Command line options are described below.  Most options may be
           changed while **less** is running, via the "-" command.
    
           Some options may be given in one of two forms: either a dash
           followed by a single letter, or two dashes followed by a long
           option name.  A long option name may be abbreviated as long as the
           abbreviation is unambiguous.  For example, --mouse may be
           abbreviated --mou, but not --mo, since both --mouse and
           --modelines begin with --mo.  Some long option names are in
           uppercase, such as --QUIT-AT-EOF, as distinct from --quit-at-eof.
           Such option names need only have their first letter capitalized;
           the remainder of the name may be in either case.  For example,
           --Quit-at-eof is equivalent to --QUIT-AT-EOF.
    
           Options are also taken from the environment variable "LESS".  For
           example, to avoid typing "less -options ..." each time **less** is
           invoked, you might tell **csh** :
    
           setenv LESS "-options"
    
           or if you use **sh** :
    
           LESS="-options"; export LESS
    
           On MS-DOS and Windows, you don't need the quotes, but you should
           be careful that any percent signs in the options string are not
           interpreted as an environment variable expansion.
    
           The environment variable is parsed before the command line, so
           command line options override the LESS environment variable.  If
           an option appears in the LESS variable, it can be reset to its
           default value on the command line by beginning the command line
           option with "-+".
    
           Some options like -k or -D require a string to follow the option
           letter.  The string for that option is considered to end when a
           dollar sign ($) is found.  For example, you can set two -D options
           like this:
    
           LESS="Dnwb$Dsbw"
    
           If the --use-backslash option appears earlier in the options, then
           a dollar sign or backslash may be included literally in an option
           string by preceding it with a backslash.  If the --use-backslash
           option is not in effect, then backslashes are not treated
           specially, and there is no way to include a dollar sign in the
           option string.
    
           -? or --help
                  This option displays a summary of the commands accepted by
                  **less**(the same as the h command).  (Depending on how your
                  shell interprets the question mark, it may be necessary to
                  quote the question mark, thus: "-\?".)
    
           -a or --search-skip-screen
                  By default, forward searches start at the top of the
                  displayed screen and backwards searches start at the bottom
                  of the displayed screen (except for repeated searches
                  invoked by the n or N commands, which start after or before
                  the "target" line respectively; see the -j option for more
                  about the target line).  The -a option causes forward
                  searches to instead start at the bottom of the screen and
                  backward searches to start at the top of the screen, thus
                  skipping all lines displayed on the screen.
    
           -A or --SEARCH-SKIP-SCREEN
                  Causes all forward searches (not just non-repeated
                  searches) to start just after the target line, and all
                  backward searches to start just before the target line.
                  Thus, forward searches will skip part of the displayed
                  screen (from the first line up to and including the target
                  line).  Similarly backwards searches will skip the
                  displayed screen from the last line up to and including the
                  target line.  This was the default behavior in less
                  versions prior to 441.
    
           -b _n_ or --buffers=_n_
                  Specifies the amount of buffer space **less** will use for each
                  file, in units of kilobytes (1024 bytes).  By default 64 KB
                  of buffer space is used for each file (unless the file is a
                  pipe; see the -B option).  The -b option specifies instead
                  that _n_ kilobytes of buffer space should be used for each
                  file.  If _n_ is -1, buffer space is unlimited; that is, the
                  entire file can be read into memory.
    
           -B or --auto-buffers
                  By default, when data is read from a pipe, buffers are
                  allocated automatically as needed.  If a large amount of
                  data is read from the pipe, this can cause a large amount
                  of memory to be allocated.  The -B option disables this
                  automatic allocation of buffers for pipes, so that only
                  64 KB (or the amount of space specified by the -b option)
                  is used for the pipe.  Warning: use of -B can result in
                  erroneous display, since only the most recently viewed part
                  of the piped data is kept in memory; any earlier data is
                  lost.  Lost characters are displayed as question marks.
    
           -c or --clear-screen
                  Causes full screen repaints to be painted from the top line
                  down.  By default, full screen repaints are done by
                  scrolling from the bottom of the screen.
    
           -C or --CLEAR-SCREEN
                  Same as -c, for compatibility with older versions of **less**.
    
           -d or --dumb
                  The -d option suppresses the error message normally
                  displayed if the terminal is dumb; that is, lacks some
                  important capability, such as the ability to clear the
                  screen or scroll backward.  The -d option does not
                  otherwise change the behavior of **less** on a dumb terminal.
    
           -D**x** _color_ or --color=**x** _color_
                  Changes the color of different parts of the displayed text.
                  **x** is a single character which selects the type of text
                  whose color is being set:
    
                  B      Binary characters.
    
                  C      Control characters.
    
                  E      Errors and informational messages.
    
                  H      Header lines and columns, set via the --header
                         option.
    
                  M      Mark letters in the status column.
    
                  N      Line numbers enabled via the -N option.
    
                  P      Prompts.
    
                  R      The rscroll character.
    
                  S      Search results.
    
                  W      The highlight enabled via the -w option.
    
                  1-5    The text in a search result which matches the first
                         through fifth parenthesized sub-pattern.  Sub-
                         pattern coloring works only if **less** is built with
                         one of the regular expression libraries **posix** , **pcre** ,
                         or **pcre2**.
    
                  d      Bold text.
    
                  k      Blinking text.
    
                  s      Standout text.
    
                  u      Underlined text.
    
                  The uppercase letters and digits can be used only when the
                  --use-color option is enabled.  When text color is
                  specified by both an uppercase letter and a lowercase
                  letter, the uppercase letter takes precedence.  For
                  example, error messages are normally displayed as standout
                  text.  So if both "s" and "E" are given a color, the "E"
                  color applies to error messages, and the "s" color applies
                  to other standout text.  The lowercase letters refer to
                  bold and underline text formed by overstriking with
                  backspaces (see the -U option) and to non-content text
                  (such as line numbers and prompts), but not to text
                  formatted using ANSI escape sequences with the -R option
                  (but see the note below for different behavior on Windows
                  and MS-DOS).
    
                  A lowercase letter may be followed by a + to indicate that
                  the normal format change and the specified color should
                  both be used.  For example, -Dug displays underlined text
                  as green without underlining; the green color has replaced
                  the usual underline formatting.  But -Du+g displays
                  underlined text as both green and in underlined format.
    
                  _color_ is either a 4-bit color string or an 8-bit color
                  string:
    
                  A 4-bit color string is one or two characters, where the
                  first character specifies the foreground color and the
                  second specifies the background color as follows:
    
                  b      Blue
    
                  c      Cyan
    
                  g      Green
    
                  k      Black
    
                  m      Magenta
    
                  r      Red
    
                  w      White
    
                  y      Yellow
    
                  The corresponding uppercase letter denotes a brighter shade
                  of the color.  For example, -DNGk displays line numbers as
                  bright green text on a black background, and -DEbR displays
                  error messages as blue text on a bright red background.  If
                  either character is a "-" or is omitted, the corresponding
                  color is set to that of normal text.
    
                  An 8-bit color string is one or two decimal integers
                  separated by a dot, where the first integer specifies the
                  foreground color and the second specifies the background
                  color.  Each integer is a value between 0 and 255 inclusive
                  which selects a "CSI 38;5" color value (see 
                  ⟨https://en.wikipedia.org/wiki/ANSI_escape_code#SGR⟩).  If
                  either integer is a "-" or is omitted, the corresponding
                  color is set to that of normal text.
    
                  A 4-bit or 8-bit color string may be followed by one or
                  more of the following characters to set text attributes in
                  addition to the color.
    
                  s or ~ Standout (reverse video)
    
                  u or _ Underline
    
                  d or * Bold
    
                  l or & Blinking
    
                  On MS-DOS and Windows, the --color option behaves
                  differently from what is described above in these ways:
    
                  •      The bold (d and *) and blinking (l and &) text
                         attributes at the end of a color string are not
                         supported.
    
                  •      Lowercase color selector letters refer to text
                         formatted by ANSI escape sequences with -R, in
                         addition to overstruck and non-content text (but see
                         -Da).
    
                  •      For historical reasons, when a lowercase color
                         selector letter is followed by a numeric color
                         value, the number is not interpreted as an "CSI
                         38;5" color value as described above, but instead as
                         a 4-bit CHAR_INFO.Attributes value, between 0 and 15
                         inclusive (see 
                         ⟨https://learn.microsoft.com/en-
                         us/windows/console/char-info-str⟩).
    
                         To avoid confusion, it is recommended that the
                         equivalent letters rather than numbers be used after
                         a lowercase color selector on MS-DOS/Windows.
    
                  •      Numeric color values ("CSI 38;5" color) following an
                         uppercase color selector letter are not supported on
                         systems earlier than Windows 10.
    
                  •      Only a limited set of ANSI escape sequences to set
                         color in the content work correctly.  4-bit color
                         sequences work, but "CSI 38;5" color sequences do
                         not.
    
                  •      The -Da option makes the behavior of --color more
                         similar to its behavior on non-MS-DOS/Windows
                         systems by (1) making lowercase color selector
                         letters not affect text formatted with ANSI escape
                         sequences, and (2) allowing "CSI 38;5" color
                         sequences in the content work by passing them to the
                         terminal (only on Windows 10 and later; on earlier
                         Windows systems, such sequences do not work
                         regardless of the setting of -Da).
    
           -e or --quit-at-eof
                  Causes **less** to automatically exit the second time it
                  reaches end-of-file.  By default, the only way to exit **less**
                  is via the "q" command.
    
           -E or --QUIT-AT-EOF
                  Causes **less** to automatically exit the first time it reaches
                  end-of-file.
    
           -f or --force
                  Forces non-regular files to be opened.  (A non-regular file
                  is a directory or a device special file.)  Also suppresses
                  the warning message when a binary file is opened.  By
                  default, **less** will refuse to open non-regular files.  Note
                  that some operating systems will not allow directories to
                  be read, even if -f is set.
    
           -F or --quit-if-one-screen
                  Causes **less** to automatically exit if the entire file can be
                  displayed on the first screen.  Also see the description of
                  the LESS_SHELL_LINES environment variable below.
    
           -g or --hilite-search
                  Normally, **less** will highlight ALL strings which match the
                  last search command.  The -g option changes this behavior
                  to highlight only the particular string which was found by
                  the last search command.  This can cause **less** to run
                  somewhat faster than the default.
    
           -G or --HILITE-SEARCH
                  The -G option suppresses all highlighting of strings found
                  by search commands.
    
           -h _n_ or --max-back-scroll=_n_
                  Specifies a maximum number of lines to scroll backward.  If
                  it is necessary to scroll backward more than _n_ lines, the
                  screen is repainted in a forward direction instead.  (If
                  the terminal does not have the ability to scroll backward,
                  -h0 is implied.)
    
           -i or --ignore-case
                  Causes searches to ignore case; that is, uppercase and
                  lowercase are considered identical.  This option is ignored
                  if any uppercase letters appear in the search pattern; in
                  other words, if a pattern contains uppercase letters, then
                  that search does not ignore case.
    
           -I or --IGNORE-CASE
                  Like -i, but searches ignore case even if the pattern
                  contains uppercase letters.
    
           -j _n_ or --jump-target=_n_
                  Specifies a line on the screen where the "target" line is
                  to be positioned.  The target line is the line specified by
                  any command to search for a pattern, jump to a line number,
                  jump to a file percentage or jump to a tag.  The screen
                  line may be specified by a number: the top line on the
                  screen is 1, the next is 2, and so on.  The number may be
                  negative to specify a line relative to the bottom of the
                  screen: the bottom line on the screen is -1, the second to
                  the bottom is -2, and so on.  Alternately, the screen line
                  may be specified as a fraction of the height of the screen,
                  starting with a decimal point: .5 is in the middle of the
                  screen, .3 is three tenths down from the first line, and so
                  on.  If the line is specified as a fraction, the actual
                  line number is recalculated if the terminal window is
                  resized.  If the --header option is used and the target
                  line specified by -j would be obscured by the header, the
                  target line is moved to the first line after the header.
    
                  If any form of the -j option is used, repeated forward
                  searches (invoked with "n" or "N") begin at the line
                  immediately after the target line, and repeated backward
                  searches begin at the target line, unless changed by -a or
                  -A.  For example, if "-j4" is used, the target line is the
                  fourth line on the screen, so forward searches begin at the
                  fifth line on the screen.  However nonrepeated searches
                  (invoked with "/" or "?")  always begin at the start or end
                  of the current screen respectively.
    
           -J or --status-column
                  Displays a status column at the left edge of the screen.
                  The character displayed in the status column may be one of:
    
                  >      The line is chopped with the -S option, and the text
                         that is chopped off beyond the right edge of the
                         screen contains a match for the current search.
    
                  <      The line is horizontally shifted, and the text that
                         is shifted beyond the left side of the screen
                         contains a match for the current search.
    
                  =      The line is both chopped and shifted, and there are
                         matches beyond both sides of the screen.
    
                  *      There are matches in the visible part of the line
                         but none to the right or left of it.
    
                  a-z, A-Z
                         The line has been marked with the corresponding
                         letter via the m or M command.
    
           -k _filename_ or --lesskey-file=_filename_
                  Causes **less** to open and interpret the named file as a
                  lesskey(1) binary file.  Multiple -k options may be
                  specified.  If the LESSKEY or LESSKEY_SYSTEM environment
                  variable is set, or if a lesskey file is found in a
                  standard place (see KEY BINDINGS), it is also used as a
                  **lesskey** file.  Note the warning under "--lesskey-content"
                  below.
    
           --lesskey-src=_filename_
                  Causes **less** to open and interpret the named file as a
                  lesskey(1) source file.  If the LESSKEYIN or
                  LESSKEYIN_SYSTEM environment variable is set, or if a
                  lesskey source file is found in a standard place (see KEY
                  BINDINGS), it is also used as a lesskey source file.  Prior
                  to version 582, the **lesskey** program needed to be run to
                  convert a lesskey _source_ file to a lesskey _binary_ file for
                  **less** to use.  Newer versions of **less** read the lesskey
                  source file directly and ignore the binary file if the
                  source file exists.  Note the warning under "--lesskey-
                  content" below.
    
           --lesskey-content=_text_
                  Causes **less** to interpret the specified text as the contents
                  of a lesskey(1) source file.  In the text, **lesskey** lines
                  may be separated by either newlines as usual, or by
                  semicolons.  A literal semicolon may be represented by a
                  backslash followed by a semicolon.
    
                  Warning: certain environment variables such as LESS,
                  LESSSECURE, LESSCHARSET and others, which are used early in
                  startup, cannot be set in a file specified by a command
                  line option (--lesskey, --lesskey-src or --lesskey-
                  content).  When using a **lesskey** file to set environment
                  variables, it is safer to use the default lesskey file, or
                  to specify the file using the LESSKEYIN or LESSKEY_CONTENT
                  environment variables rather than using a command line
                  option.
    
           -K or --quit-on-intr
                  Causes **less** to exit immediately (with status 2) when an
                  interrupt character (usually ^C) is typed.  Normally, an
                  interrupt character causes **less** to stop whatever it is
                  doing and return to its command prompt.  Note that use of
                  this option makes it impossible to return to the command
                  prompt from the "F" command.
    
           -L or --no-lessopen
                  Ignore the LESSOPEN environment variable (see the INPUT
                  PREPROCESSOR section below).  This option can be set from
                  within **less** , but it will apply only to files opened
                  subsequently, not to the file which is currently open.
    
           -m or --long-prompt
                  Causes **less** to prompt verbosely (like more(1)), with the
                  percent into the file.  By default, **less** prompts with a
                  colon.
    
           -M or --LONG-PROMPT
                  Causes **less** to prompt even more verbosely than more(1).
    
           -n or --line-numbers
                  Suppresses line numbers.  The default (to use line numbers)
                  may cause **less** to run more slowly in some cases, especially
                  with a very large input file.  Using line numbers means:
                  the line number will be displayed in the verbose prompt and
                  in the = command, and the v command will pass the current
                  line number to the editor (see also the discussion of
                  LESSEDIT in PROMPTS below).
    
           -N or --LINE-NUMBERS
                  Causes a line number to be displayed at the beginning of
                  each line in the display.
    
           -o _filename_ or --log-file=_filename_
                  Causes **less** to copy its input to the named file as it is
                  being viewed.  This applies only when the input file is a
                  pipe, not an ordinary file.  If the file already exists,
                  **less** will ask for confirmation before overwriting it.
    
           -O _filename_ or --LOG-FILE=_filename_
                  The -O option is like -o, but it will overwrite an existing
                  file without asking for confirmation.
    
                  If no log file has been specified, the -o and -O options
                  can be used from within **less** to specify a log file.
                  Without a file name, they will simply report the name of
                  the log file.  The "s" command is equivalent to specifying
                  -o from within **less**.
    
           -p _pattern_ or --pattern=_pattern_
                  The -p option on the command line is equivalent to
                  specifying +/_pattern_ ; that is, it tells **less** to start at
                  the first occurrence of _pattern_ in the file.
    
           -P _prompt_ or --prompt=_prompt_
                  Provides a way to tailor the three prompt styles to your
                  own preference.  This option would normally be put in the
                  LESS environment variable, rather than being typed in with
                  each **less** command.  Such an option must either be the last
                  option in the LESS variable, or be terminated by a dollar
                  sign.
                   -Ps followed by a string changes the default (short)
                  prompt to that string.
                   -Pm changes the medium (-m) prompt.
                   -PM changes the long (-M) prompt.
                   -Ph changes the prompt for the help screen.
                   -P= changes the message printed by the = command.
                   -Pw changes the message printed while waiting for data (in
                  the "F" command).
    
                  All prompt strings consist of a sequence of letters and
                  special escape sequences.  See the section on PROMPTS for
                  more details.
    
           -q or --quiet or --silent
                  Causes moderately "quiet" operation: the terminal bell is
                  not rung if an attempt is made to scroll past the end of
                  the file or before the beginning of the file.  If the
                  terminal has a "visual bell", it is used instead.  The bell
                  will be rung on certain other errors, such as typing an
                  invalid character.  The default is to ring the terminal
                  bell in all such cases.
    
           -Q or --QUIET or --SILENT
                  Causes totally "quiet" operation: the terminal bell is
                  never rung.  If the terminal has a "visual bell", it is
                  used in all cases where the terminal bell would have been
                  rung.
    
           -r or --raw-control-chars
                  Causes "raw" control characters to be displayed.  The
                  default is to display control characters using the caret
                  notation; for example, a control-A (octal 001) is displayed
                  as "^A" (with some exceptions as described under the -U
                  option).  Warning: when the -r option is used, **less** cannot
                  keep track of the actual appearance of the screen (since
                  this depends on how the screen responds to each type of
                  control character).  Thus, various display problems may
                  result, such as long lines being split in the wrong place.
    
                  USE OF THE -r OPTION IS DANGEROUS AND IS NOT RECOMMENDED.
                  The -r option can be set on the command line or via the -
                  command, but to avoid unintentional use, it cannot be set
                  in a LESS environment variable.  If -r appears in a LESS
                  environment variable, it is treated as if it were -R.
    
           -R or --RAW-CONTROL-CHARS
                  Like -r, but only a limited set of escape sequences are
                  output in "raw" form.  Unlike -r, the screen appearance is
                  maintained correctly.  The sequences which are output raw
                  are:
    
                  1. ANSI SGR ("color") sequences
    
                  2. OSC 8 hyperlinks
    
                  3. Other OSC sequences, if the OSC type number is listed in
                  the LESSANSIOSCALLOW environment variable
    
                  4. OSC sequences starting with a non-standard introductory
                  character (that is, something other than "]"), if the
                  character is listed in the LESSANSIOSCCHARS environment
                  variable followed by an asterisk
    
                  ANSI color escape sequences are sequences of the form:
    
                       ESC [ ... m
    
                  where the "..." is zero or more color specification
                  characters.  Color escape sequences are only supported when
                  the color is changed within one line, not across lines.  In
                  other words, the beginning of each line is assumed to be
                  normal (non-colored), regardless of any escape sequences in
                  previous lines.
    
                  You can make **less** think that characters other than "m" can
                  end ANSI color escape sequences by setting the environment
                  variable LESSANSIENDCHARS to the list of characters which
                  can end a color escape sequence.  And you can make **less**
                  think that characters other than the standard ones may
                  appear between the ESC and the m by setting the environment
                  variable LESSANSIMIDCHARS to the list of characters which
                  can appear.
    
                  OSC sequences are of the form:
    
                       ESC ] N ; ... \7
    
                  where the OSC type number N is a decimal integer.  The
                  terminating sequence may be either a BEL character (\7) as
                  above, or the two-character sequence "ESC \".
    
           -s or --squeeze-blank-lines
                  Causes consecutive blank lines to be squeezed into a single
                  blank line.  This is useful when viewing nroff(1) output.
    
           -S or --chop-long-lines
                  Causes lines longer than the screen width to be chopped
                  (truncated) rather than wrapped.  That is, the portion of a
                  long line that does not fit in the screen width is not
                  displayed until you press RIGHT-ARROW.  The default is to
                  wrap long lines; that is, display the remainder on the next
                  line.  See also the --wordwrap option.  While the --header
                  option is active, the -S option is ignored, and lines
                  longer than the screen width are truncated.
    
           -t _tag_ or --tag=_tag_
                  The -t option, followed immediately by a TAG, will edit the
                  file containing that tag.  For this to work, tag
                  information must be available; for example, there may be a
                  file in the current directory called "tags", which was
                  previously built by **ctags**(1) or an equivalent command.  If
                  the environment variable LESSGLOBALTAGS is set, it is taken
                  to be the name of a command compatible with **global**(1), and
                  that command is executed to find the tag.  (See 
                  ⟨http://www.gnu.org/software/global/global.html⟩).  The -t
                  option may also be specified from within **less**(using the -
                  command) as a way of examining a new file.  The command
                  ":t" is equivalent to specifying -t from within **less**.
    
           -T _tagsfile_ or --tag-file=_tagsfile_
                  Specifies a tags file to be used instead of "tags".
    
           -u or --underline-special
                  Causes backspaces and carriage returns to be treated as
                  printable characters; that is, they are sent to the
                  terminal when they appear in the input.
    
           -U or --UNDERLINE-SPECIAL
                  Causes backspaces, tabs, carriage returns and "formatting
                  characters" (as defined by Unicode) to be treated as
                  control characters; that is, they are handled as specified
                  by the -r option.
    
                  By default, if neither -u nor -U is given, backspaces which
                  appear adjacent to an underscore character are treated
                  specially: the underlined text is displayed using the
                  terminal's hardware underlining capability.  Also,
                  backspaces which appear between two identical characters
                  are treated specially: the overstruck text is printed using
                  the terminal's hardware boldface capability.  Other
                  backspaces are deleted, along with the preceding character.
                  Carriage returns immediately followed by a newline are
                  deleted.  Other carriage returns are handled as specified
                  by the -r option.  Unicode formatting characters, such as
                  the Byte Order Mark, are sent to the terminal.  Text which
                  is overstruck or underlined can be searched for if neither
                  -u nor -U is in effect.
    
                  See also the --proc-backspace, --proc-tab, and --proc-
                  return options.
    
           -V or --version
                  Displays the version number of **less**.
    
           -w or --hilite-unread
                  Temporarily highlights the first "new" line after a forward
                  movement of a full page.  The first "new" line is the line
                  immediately following the line previously at the bottom of
                  the screen.  Also highlights the target line after a g or p
                  command.  The highlight is removed at the next command
                  which causes movement.  If the --status-line option is in
                  effect, the entire line (the width of the screen) is
                  highlighted.  Otherwise, only the text in the line is
                  highlighted, unless the -J option is in effect, in which
                  case only the status column is highlighted.
    
           -W or --HILITE-UNREAD
                  Like -w, but temporarily highlights the first new line
                  after any forward movement command larger than one line.
    
           -x _n_ ,... or --tabs=_n_ ,...
                  Sets tab stops.  If only one _n_ is specified, tab stops are
                  set at multiples of _n_.  If multiple values separated by
                  commas are specified, tab stops are set at those positions,
                  and then continue with the same spacing as the last two.
                  For example, "-x9,17" will set tabs at positions 9, 17, 25,
                  33, etc.  The default for _n_ is 8.
    
           -X or --no-init
                  Disables sending the termcap initialization and
                  deinitialization strings to the terminal.  This is
                  sometimes desirable if the deinitialization string does
                  something unnecessary, like clearing the screen.
    
           -y _n_ or --max-forw-scroll=_n_
                  Specifies a maximum number of lines to scroll forward.  If
                  it is necessary to scroll forward more than _n_ lines, the
                  screen is repainted instead.  The -c or -C option may be
                  used to repaint from the top of the screen if desired.  By
                  default, any forward movement causes scrolling.
    
           -z _n_ or --window=_n_ or -_n_
                  Changes the default scrolling window size to _n_ lines.  The
                  default is one screenful.  The z and w commands can also be
                  used to change the window size.  The "z" may be omitted for
                  compatibility with some versions of more(1).  If the number
                  _n_ is negative, it indicates _n_ lines less than the current
                  screen size.  For example, if the screen is 24 lines, _-z-4_
                  sets the scrolling window to 20 lines.  If the screen is
                  resized to 40 lines, the scrolling window automatically
                  changes to 36 lines.
    
           -"_cc_ or --quotes=_cc_
                  Changes the filename quoting character.  This may be
                  necessary if you are trying to name a file which contains
                  both spaces and quote characters.  Followed by a single
                  character, this changes the quote character to that
                  character.  Filenames containing a space should then be
                  surrounded by that character rather than by double quotes.
                  Followed by two characters, changes the open quote to the
                  first character, and the close quote to the second
                  character.  Filenames containing a space should then be
                  preceded by the open quote character and followed by the
                  close quote character.  Note that even after the quote
                  characters are changed, this option remains -" (a dash
                  followed by a double quote).
    
           -~ or --tilde
                  Normally lines after end of file are displayed as a single
                  tilde (~).  This option causes lines after end of file to
                  be displayed as blank lines.
    
           -# or --shift
                  Specifies the default number of positions to scroll
                  horizontally in the RIGHTARROW and LEFTARROW commands.  If
                  the number specified is zero, it sets the default number of
                  positions to one half of the screen width.  Alternately,
                  the number may be specified as a fraction of the width of
                  the screen, starting with a decimal point: .5 is half of
                  the screen width, .3 is three tenths of the screen width,
                  and so on.  If the number is specified as a fraction, the
                  actual number of scroll positions is recalculated if the
                  terminal window is resized.
    
           --exit-follow-on-close
                  When using the "F" command on a pipe, **less** will
                  automatically stop waiting for more data when the input
                  side of the pipe is closed.
    
           --file-size
                  If --file-size is specified, **less** will determine the size
                  of the file immediately after opening the file.  Then the
                  "=" command will display the number of lines in the file.
                  Normally this is not done, because it can be slow if the
                  input file is non-seekable (such as a pipe) and is large.
    
           --follow-name
                  Normally, if the input file is renamed while an F command
                  is executing, **less** will continue to display the contents of
                  the original file despite its name change.  If --follow-
                  name is specified, during an F command **less** will
                  periodically attempt to reopen the file by name.  If the
                  reopen succeeds and the file is a different file from the
                  original (which means that a new file has been created with
                  the same name as the original (now renamed) file), **less**
                  will display the contents of that new file.
    
           --form-feed
                  When scrolling forward or backward in the file, stop if a
                  line beginning with a form feed character (^L) is reached.
                  This can be useful when viewing a file which uses form
                  feeds between pages.
    
           --header=_L_ ,_C_ ,_N_
                  Sets the number of header lines and columns displayed on
                  the screen.  The number of header lines is set to _L_.  If _L_
                  is 0, header lines are disabled.  If _L_ is empty or missing,
                  the number of header lines is unchanged.  The number of
                  header columns is set to _C_.  If _C_ is 0, header columns are
                  disabled.  If _C_ is empty or missing, the number of header
                  columns is unchanged.  The first header line is set to line
                  number _N_ in the file.  If _N_ is empty or missing, it is
                  taken to be the number of the line currently displayed in
                  the first line of the screen (if the --header command has
                  been issued from within **less**), or 1 (if the --header option
                  has been given on the command line).  The special form
                  "--header=-" disables header lines and header columns, and
                  is equivalent to "--header=0,0".
    
                  When _L_ is nonzero, the first _L_ lines at the top of the
                  screen are replaced with the _L_ lines of the file beginning
                  at line _N_ , regardless of what part of the file is being
                  viewed.  When header lines are displayed, any file contents
                  before the header line cannot be viewed.  When _C_ is
                  nonzero, the first _C_ characters displayed at the beginning
                  of each line are replaced with the first _C_ characters of
                  the line, even if the rest of the line is scrolled
                  horizontally.
    
                  While the --header option is active, lines longer than the
                  screen width are truncated, and the -S option is ignored.
    
           --incsearch
                  Subsequent search commands will be "incremental"; that is,
                  **less** will advance to the next line containing the search
                  pattern as each character of the pattern is typed in.
    
           --intr=_c_
                  Use the character _c_ instead of ^X to interrupt a read when
                  the "Waiting for data" message is displayed.  _c_ must be an
                  ASCII character; that is, one with a value between 1 and
                  127 inclusive.  A caret followed by a single character can
                  be used to specify a control character.
    
           --line-num-width=_n_
                  Sets the minimum width of the line number field when the -N
                  option is in effect to _n_ characters.  The default is 7.
    
           --match-shift=_n_
                  When -S is in effect, if a search match is not visible
                  because it is shifted to the left or right of the currently
                  visible screen, the text will horizontally shift to ensure
                  that the search match is visible.  This option selects the
                  column in which the first character of the search match
                  will be placed after the shift.  In other words, there will
                  be _n_ characters visible to the left of the search match.
    
                  Alternately, the number may be specified as a fraction of
                  the width of the screen, starting with a decimal point: .5
                  is half of the screen width, .3 is three tenths of the
                  screen width, and so on.  If the number is specified as a
                  fraction, the actual number of scroll positions is
                  recalculated if the terminal window is resized.
    
           --modelines=_n_
                  Before displaying a file, **less** will read the first _n_ lines
                  to try to find a vim-compatible _modeline_.  If _n_ is zero,
                  **less** does not try to find modelines.  By using a modeline,
                  the file itself can specify the tab stops that should be
                  used when viewing it.
    
                  A modeline contains, anywhere in the line, a program name
                  ("vi", "vim", "ex", or "less"), followed by a colon,
                  possibly followed by the word "set", and finally followed
                  by zero or more option settings.  If the word "set" is
                  used, option settings are separated by spaces, and end at
                  the first colon.  If the word "set" is not used, option
                  settings may be separated by either spaces or colons.  The
                  word "set" is required if the program name is "less" but
                  optional if any of the other three names are used.  If any
                  option setting is of the form "tabstop=_n_ " or "ts=_n_ ", then
                  tab stops are automatically set as if --tabs=_n_ had been
                  given.  See the --tabs description for acceptable values of
                  _n_.
    
           --mouse
                  Enables mouse input: scrolling the mouse wheel down moves
                  forward in the file, scrolling the mouse wheel up moves
                  backwards in the file, left-click sets the "#" mark to the
                  line where the mouse is clicked, and right-click (or any
                  other) returns to the "#" mark position.  Holding down the
                  left button and dragging also moves in the file.  If a
                  left-click is performed with the mouse cursor on an OSC 8
                  hyperlink, the hyperlink is selected as if by the ^O^N
                  command.  If a left-click is performed with the mouse
                  cursor on an OSC 8 hyperlink which is already selected, the
                  hyperlink is opened as if by the ^O^O command.  The number
                  of lines to scroll when the wheel is moved can be set by
                  the --wheel-lines option.  Mouse input works only on
                  terminals which support X11 mouse reporting, and on the
                  Windows version of **less**.
    
           --MOUSE
                  Like --mouse, except the direction scrolled on mouse wheel
                  movement is reversed.
    
           --no-edit-warn
                  Don't print a warning message when using the v command on a
                  file which was opened using a LESSOPEN preprocessor (see
                  the INPUT PREPROCESSOR section below).
    
           --no-keypad
                  Disables sending the keypad initialization and
                  deinitialization strings to the terminal.  This is
                  sometimes useful if the keypad strings make the numeric
                  keypad behave in an undesirable manner.
    
           --no-histdups
                  This option changes the behavior so that if a search string
                  or file name is typed in, and the same string is already in
                  the history list, the existing copy is removed from the
                  history list before the new one is added.  Thus, a given
                  string will appear only once in the history list.
                  Normally, a string may appear multiple times.
    
           --no-number-headers
                  Header lines (defined via the --header option) are not
                  assigned line numbers.  Line number 1 is assigned to the
                  first line after any header lines.
    
           --no-paste
                  If the terminal supports xterm-compatible "bracketed
                  paste", any text pasted into **less** is ignored, except that
                  one line of text may be pasted into the command line at the
                  bottom of the screen (search strings, file names, etc).
                  That is, the first newline of text pasted into the command
                  line and any text that follows it is ignored.
    
           --no-search-header-lines
                  Searches do not include header lines, but still include
                  header columns.
    
           --no-search-header-columns
                  Searches do not include header columns, but still include
                  header lines.
    
           --no-search-headers
                  Searches do not include header lines or header columns.
    
           --no-vbell
                  Disables the terminal's visual bell.
    
           --proc-backspace
                  If set, backspaces are handled as if neither the -u option
                  nor the -U option were set.  That is, a backspace adjacent
                  to an underscore causes text to be displayed in underline
                  mode, and a backspace between identical characters cause
                  text to be displayed in boldface mode.  This option
                  overrides the -u and -U options, so that display of
                  backspaces can be controlled separate from tabs and
                  carriage returns.  If not set, backspace display is
                  controlled by the -u and -U options.
    
           --PROC-BACKSPACE
                  If set, backspaces are handled as if the -U option were
                  set; that is backspaces are treated as control characters.
    
           --proc-return
                  If set, carriage returns are handled as if neither the -u
                  option nor the -U option were set.  That is, a carriage
                  return immediately before a newline is deleted.  This
                  option overrides the -u and -U options, so that display of
                  carriage returns can be controlled separate from that of
                  backspaces and tabs.  If not set, carriage return display
                  is controlled by the -u and -U options.
    
           --PROC-RETURN
                  If set, carriage returns are handled as if the -U option
                  were set; that is carriage returns are treated as control
                  characters.
    
           --proc-tab
                  If set, tabs are handled as if the -U option were not set.
                  That is, tabs are expanded to spaces.  This option
                  overrides the -U option, so that display of tabs can be
                  controlled separate from that of backspaces and carriage
                  returns.  If not set, tab display is controlled by the -U
                  option.
    
           --PROC-TAB
                  If set, tabs are handled as if the -U option were set; that
                  is tabs are treated as control characters.
    
           --redraw-on-quit
                  When quitting, after sending the terminal deinitialization
                  string, redraws the entire last screen.  On terminals whose
                  terminal deinitialization string causes the terminal to
                  switch from an alternate screen, this makes the last
                  screenful of the current file remain visible after **less** has
                  quit.
    
           --rscroll=_c_
                  This option changes the character used to mark truncated
                  lines.  It may begin with a two-character attribute
                  indicator like LESSBINFMT does.  If there is no attribute
                  indicator, standout is used.  If set to "-", truncated
                  lines are not marked.
    
           --save-marks
                  Save marks in the history file, so marks are retained
                  across different invocations of **less**.
    
           --search-options=_..._
                  Sets default search modifiers.  The value is a string of
                  one or more of the characters E, F, K, N, R or W.  Setting
                  any of these has the same effect as typing that control
                  character at the beginning of every search pattern.  For
                  example, setting --search-options=W is the same as typing
                  ^W at the beginning of every pattern.  The value may also
                  contain a digit between 1 and 5, which has the same effect
                  as typing ^S followed by that digit at the beginning of
                  every search pattern.  The value "-" disables all default
                  search modifiers.
    
           --show-preproc-errors
                  If a preprocessor produces data, then exits with a non-zero
                  exit code, **less** will display a warning.
    
           --status-col-width=_n_
                  Sets the width of the status column when the -J option is
                  in effect.  The default is 2 characters.
    
           --status-line
                  If a line is marked, the entire line (rather than just the
                  status column) is highlighted.  Also lines highlighted due
                  to the -w option will have the entire line highlighted.  If
                  --use-color is set, the line is colored rather than
                  highlighted.
    
           --use-backslash
                  This option changes the interpretations of options which
                  follow this one.  After the --use-backslash option, any
                  backslash in an option string is removed and the following
                  character is taken literally.  This allows a dollar sign to
                  be included in option strings.
    
           --use-color
                  Enables colored text in various places.  The -D option can
                  be used to change the colors.  Colored text works only if
                  the terminal supports ANSI color escape sequences (as
                  defined in 
                  ⟨https://www.ecma-international.org/publications-and-
                  standards/standards/ecma-48⟩).
    
           --wheel-lines=_n_
                  Set the number of lines to scroll when the mouse wheel is
                  scrolled and the --mouse or --MOUSE option is in effect.
                  The default is 1 line.
    
           --wordwrap
                  When the -S option is not in use, wrap each line at a space
                  or tab if possible, so that a word is not split between two
                  lines.  The default is to wrap at any character.
    
           --     A command line argument of "--" marks the end of option
                  arguments.  Any arguments following this are interpreted as
                  filenames.  This can be useful when viewing a file whose
                  name begins with a "-" or "+".
    
           +      If a command line option begins with **+** , the remainder of
                  that option is taken to be an initial command to **less**.  For
                  example, +G tells **less** to start at the end of the file
                  rather than the beginning, and +/xyz tells it to start at
                  the first occurrence of "xyz" in the file.  As a special
                  case, +<number> acts like +<number>g; that is, it starts
                  the display at the specified line number (however, see the
                  caveat under the "g" command above).  If the option starts
                  with ++, the initial command applies to every file being
                  viewed, not just the first one.  The + command described
                  previously may also be used to set (or change) an initial
                  command for every file.
    


## LINE EDITING



           When entering a command line at the bottom of the screen (for
           example, a filename for the :e command, or the pattern for a
           search command), certain keys can be used to manipulate the
           command line.  Most commands have an alternate form in [ brackets
           ] which can be used if a key does not exist on a particular
           keyboard.  (Note that the forms beginning with ESC do not work on
           some MS-DOS and Windows systems because ESC is the line erase
           character.)  Any of these special keys may be entered literally by
           preceding it with the "literal" character, either ^V or ^A.  A
           backslash itself may also be entered literally by entering two
           backslashes.
    
           LEFTARROW [ ESC-h ]
                  Move the cursor one space to the left.
    
           RIGHTARROW [ ESC-l ]
                  Move the cursor one space to the right.
    
           ^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
                  (That is, CONTROL and LEFTARROW simultaneously.)  Move the
                  cursor one word to the left.
    
           ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]
                  (That is, CONTROL and RIGHTARROW simultaneously.)  Move the
                  cursor one word to the right.
    
           HOME [ ESC-0 ]
                  Move the cursor to the beginning of the line.
    
           END [ ESC-$ ]
                  Move the cursor to the end of the line.
    
           BACKSPACE
                  Delete the character to the left of the cursor, or cancel
                  the command if the command line is empty.
    
           DELETE or [ ESC-x ]
                  Delete the character under the cursor.
    
           ^BACKSPACE [ ESC-BACKSPACE ]
                  (That is, CONTROL and BACKSPACE simultaneously.)  Delete
                  the word to the left of the cursor.
    
           ^DELETE [ ESC-X or ESC-DELETE ]
                  (That is, CONTROL and DELETE simultaneously.)  Delete the
                  word under the cursor.
    
           UPARROW [ ESC-k ]
                  Retrieve the previous command line.  If you first enter
                  some text and then press UPARROW, it will retrieve the
                  previous command which begins with that text.
    
           DOWNARROW [ ESC-j ]
                  Retrieve the next command line.  If you first enter some
                  text and then press DOWNARROW, it will retrieve the next
                  command which begins with that text.
    
           TAB    Complete the partial filename to the left of the cursor.
                  If it matches more than one filename, the first match is
                  entered into the command line.  Repeated TABs will cycle
                  thru the other matching filenames.  If the completed
                  filename is a directory, a "/" is appended to the filename.
                  (On MS-DOS and Windows systems, a "\" is appended.)  The
                  environment variable LESSSEPARATOR can be used to specify a
                  different character to append to a directory name.
    
           BACKTAB [ ESC-TAB ]
                  Like, TAB, but cycles in the reverse direction thru the
                  matching filenames.
    
           ^L     Complete the partial filename to the left of the cursor.
                  If it matches more than one filename, all matches are
                  entered into the command line (if they fit).
    
           ^U (Unix and OS/2) or ESC (MS-DOS and Windows)
                  Delete the entire command line, or cancel the command if
                  the cursor is at the beginning of the command line.  If you
                  have changed your line-kill character in Unix to something
                  other than ^U, that character is used instead of ^U.
    
           ^G     Delete the entire command line and return to the main
                  prompt.
    


## KEY BINDINGS



           You may define your own **less** commands by creating a lesskey source
           file.  This file specifies a set of command keys and an action
           associated with each key.  You may also change the line-editing
           keys (see LINE EDITING), and set environment variables used by
           **less**.  See the lesskey(1) manual page for details about the file
           format.
    
           If the environment variable LESSKEYIN is set, **less** uses that as
           the name of the lesskey source file.  Otherwise, **less** looks in a
           standard place for the lesskey source file: On Unix systems, **less**
           looks for a lesskey file called "$XDG_CONFIG_HOME/lesskey" or
           "$HOME/.config/lesskey" or "$HOME/.lesskey".  On MS-DOS and
           Windows systems, **less** looks for a lesskey file called
           "$HOME/_lesskey", and if it is not found there, then looks for a
           lesskey file called "_lesskey" in any directory specified in the
           PATH environment variable.  On OS/2 systems, **less** looks for a
           lesskey file called "$HOME/lesskey.ini", and if it is not found,
           then looks for a lesskey file called "lesskey.ini" in any
           directory specified in the INIT environment variable, and if it
           not found there, then looks for a lesskey file called
           "lesskey.ini" in any directory specified in the PATH environment
           variable.
    
           A system-wide lesskey source file may also be set up to provide
           key bindings.  If a key is defined in both a local lesskey file
           and in the system-wide file, key bindings in the local file take
           precedence over those in the system-wide file.  If the environment
           variable LESSKEYIN_SYSTEM is set, **less** uses that as the name of
           the system-wide lesskey file.  Otherwise, **less** looks in a standard
           place for the system-wide lesskey file: On Unix systems, the
           system-wide lesskey file is /usr/local/etc/syslesskey.  (However,
           if **less** was built with a different sysconf directory than
           /usr/local/etc, that directory is where the sysless file is
           found.)  On MS-DOS and Windows systems, the system-wide lesskey
           file is c:\_syslesskey.  On OS/2 systems, the system-wide lesskey
           file is c:\syslesskey.ini.
    
           Older versions of **less**(before v582) used lesskey files with a
           binary format, produced by the **lesskey** program. It is no longer
           necessary to use the **lesskey** program.
    


## INPUT PREPROCESSOR



           You may define an "input preprocessor" for **less**.  Before **less**
           opens a file, it first gives the input preprocessor a chance to
           modify the way the contents of the file are displayed.  An input
           preprocessor is simply an executable program (or shell script),
           which writes the contents of the file to a different file, called
           the replacement file.  The contents of the replacement file are
           then displayed in place of the contents of the original file.
           However, it will appear to the user as if the original file is
           opened; that is, **less** will display the original filename as the
           name of the current file.
    
           An input preprocessor receives one command line argument, the
           original filename, as entered by the user.  It should create the
           replacement file, and when finished, print the name of the
           replacement file to its standard output.  If the input
           preprocessor does not output a replacement filename, **less** uses the
           original file, as normal.  The input preprocessor is not called
           when viewing standard input.  To set up an input preprocessor, set
           the LESSOPEN environment variable to a command line which will
           invoke your input preprocessor.  This command line should include
           one occurrence of the string "%s", which will be replaced by the
           filename when the input preprocessor command is invoked.
    
           When **less** closes a file opened in such a way, it will call another
           program, called the input postprocessor, which may perform any
           desired clean-up action (such as deleting the replacement file
           created by LESSOPEN).  This program receives two command line
           arguments, the original filename as entered by the user, and the
           name of the replacement file.  To set up an input postprocessor,
           set the LESSCLOSE environment variable to a command line which
           will invoke your input postprocessor.  It may include two
           occurrences of the string "%s"; the first is replaced with the
           original name of the file and the second with the name of the
           replacement file, which was output by LESSOPEN.
    
           For example, on many Unix systems, these two scripts will allow
           you to keep files in compressed format, but still let **less** view
           them directly:
    
           lessopen.sh:
                #! /bin/sh
                case "$1" in
                *.Z) TEMPFILE=$(mktemp)
                     uncompress -c $1  >$TEMPFILE  2>/dev/null
                     if [ -s $TEMPFILE ]; then
                          echo $TEMPFILE
                     else
                          rm -f $TEMPFILE
                     fi
                     ;;
                esac
    
           lessclose.sh:
                #! /bin/sh
                rm $2
    
           To use these scripts, put them both where they can be executed and
           set LESSOPEN="lessopen.sh %s", and LESSCLOSE="lessclose.sh %s %s".
           More complex LESSOPEN and LESSCLOSE scripts may be written to
           accept other types of compressed files, and so on.
    
           It is also possible to set up an input preprocessor to pipe the
           file data directly to **less** , rather than putting the data into a
           replacement file.  This avoids the need to decompress the entire
           file before starting to view it.  An input preprocessor that works
           this way is called an input pipe.  An input pipe, instead of
           writing the name of a replacement file on its standard output,
           writes the entire contents of the replacement file on its standard
           output.  If the input pipe does not write any characters on its
           standard output, then there is no replacement file and **less** uses
           the original file, as normal.  To use an input pipe, make the
           first character in the LESSOPEN environment variable a vertical
           bar (|) to signify that the input preprocessor is an input pipe.
           As with non-pipe input preprocessors, the command string must
           contain one occurrence of %s, which is replaced with the filename
           of the input file.
    
           For example, on many Unix systems, this script will work like the
           previous example scripts:
    
           lesspipe.sh:
                #! /bin/sh
                case "$1" in
                *.Z) uncompress -c $1  2>/dev/null
                     ;;
                *)   exit 1
                     ;;
                esac
                exit $?
    
           To use this script, put it where it can be executed and set
           LESSOPEN="|lesspipe.sh %s".
    
           Note that a preprocessor cannot output an empty file, since that
           is interpreted as meaning there is no replacement, and the
           original file is used.  To avoid this, if LESSOPEN starts with two
           vertical bars, the exit status of the script determines the
           behavior when the output is empty.  If the output is empty and the
           exit status is zero, the empty output is considered to be
           replacement text.  If the output is empty and the exit status is
           nonzero, the original file is used.  For compatibility with
           previous versions of **less** , if LESSOPEN starts with only one
           vertical bar, the exit status of the preprocessor is ignored.
    
           When an input pipe is used, a LESSCLOSE postprocessor can be used,
           but it is usually not necessary since there is no replacement file
           to clean up.  In this case, the replacement file name passed to
           the LESSCLOSE postprocessor is "-".
    
           For compatibility with previous versions of **less** , the input
           preprocessor or pipe is not used if **less** is viewing standard
           input.  However, if the first character of LESSOPEN is a dash (-),
           the input preprocessor is used on standard input as well as other
           files.  In this case, the dash is not considered to be part of the
           preprocessor command.  If standard input is being viewed, the
           input preprocessor is passed a file name consisting of a single
           dash.  Similarly, if the first two characters of LESSOPEN are
           vertical bar and dash (|-) or two vertical bars and a dash (||-),
           the input pipe is used on standard input as well as other files.
           Again, in this case the dash is not considered to be part of the
           input pipe command.
    


## NATIONAL CHARACTER SETS



           There are three types of characters in the input file:
    
           normal characters
                  can be displayed directly to the screen.
    
           control characters
                  should not be displayed directly, but are expected to be
                  found in ordinary text files (such as backspace and tab).
    
           binary characters
                  should not be displayed directly and are not expected to be
                  found in text files.
    
           A "character set" is simply a description of which characters are
           to be considered normal, control, and binary.  The LESSCHARSET
           environment variable may be used to select a character set.
           Possible values for LESSCHARSET are:
    
           ascii  BS, TAB, NL, CR, and formfeed are control characters, all
                  chars with values between 32 and 126 are normal, and all
                  others are binary.
    
           iso8859
                  Selects an ISO 8859 character set.  This is the same as
                  ASCII, except characters between 160 and 255 are treated as
                  normal characters.
    
           latin1 Same as iso8859.
    
           latin9 Same as iso8859.
    
           dos    Selects a character set appropriate for MS-DOS.
    
           ebcdic Selects an EBCDIC character set.
    
           IBM-1047
                  Selects an EBCDIC character set used by OS/390 Unix
                  Services.  This is the EBCDIC analogue of latin1.  You get
                  similar results by setting either LESSCHARSET=IBM-1047 or
                  LC_CTYPE=en_US in your environment.
    
           koi8-r Selects a Russian character set.
    
           next   Selects a character set appropriate for NeXT computers.
    
           utf-8  Selects the UTF-8 encoding of the ISO 10646 character set.
                  UTF-8 is special in that it supports multi-byte characters
                  in the input file.  It is the only character set that
                  supports multi-byte characters.
    
           windows
                  Selects a character set appropriate for Microsoft Windows
                  (cp 1252).
    
           In rare cases, it may be desired to tailor **less** to use a character
           set other than the ones definable by LESSCHARSET.  In this case,
           the environment variable LESSCHARDEF can be used to define a
           character set.  It should be set to a string where each character
           in the string represents one character in the character set.  The
           character "." is used for a normal character, "c" for control, and
           "b" for binary.  A decimal number may be used for repetition.  For
           example, "bccc4b." would mean character 0 is binary, 1, 2 and 3
           are control, 4, 5, 6 and 7 are binary, and 8 is normal.  All
           characters after the last are taken to be the same as the last, so
           characters 9 through 255 would be normal.  (This is an example,
           and does not necessarily represent any real character set.)
    
           This table shows the value of LESSCHARDEF which is equivalent to
           each of the possible values for LESSCHARSET:
                ascii      8bcccbcc18b95.b
                dos        8bcccbcc12bc5b95.b.
                ebcdic     5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
                           9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
                IBM-1047   4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
                           191.b
                iso8859    8bcccbcc18b95.33b.
                koi8-r     8bcccbcc18b95.b128.
                latin1     8bcccbcc18b95.33b.
                next       8bcccbcc18b95.bb125.bb
    
           If neither LESSCHARSET nor LESSCHARDEF is set, but any of the
           strings "UTF-8", "UTF8", "utf-8" or "utf8" is found in the LC_ALL,
           LC_CTYPE or LANG environment variables, then the default character
           set is utf-8.
    
           If that string is not found, but your system supports the
           **setlocale** interface, **less** will use setlocale to determine the
           character set.  setlocale is controlled by setting the LANG or
           LC_CTYPE environment variables.
    
           Finally, if the _setlocale_ interface is also not available, the
           default character set is utf-8.
    
           Control and binary characters are displayed in standout (reverse
           video).  Each such character is displayed in caret notation if
           possible (e.g. ^A for control-A).  Caret notation is used only if
           inverting the 0100 bit results in a normal printable character.
           Otherwise, the character is displayed as a hex number in angle
           brackets.  This format can be changed by setting the LESSBINFMT
           environment variable.  LESSBINFMT may begin with a "*" and one
           character to select the display attribute: "*k" is blinking, "*d"
           is bold, "*u" is underlined, "*s" is standout, and "*n" is normal.
           If LESSBINFMT does not begin with a "*", normal attribute is
           assumed.  The remainder of LESSBINFMT is a string which may
           include one printf-style escape sequence (a % followed by x, X, o,
           d, etc.).  For example, if LESSBINFMT is "*u[%x]", binary
           characters are displayed in underlined hexadecimal surrounded by
           brackets.  The default if no LESSBINFMT is specified is
           "*s<%02X>".  Warning: the result of expanding the character via
           LESSBINFMT must be less than 31 characters.
    
           When the character set is utf-8, the LESSUTFBINFMT environment
           variable acts similarly to LESSBINFMT but it applies to Unicode
           code points that were successfully decoded but are unsuitable for
           display (e.g., unassigned code points).  Its default value is
           "<U+%04lX>".  Note that LESSUTFBINFMT and LESSBINFMT share their
           display attribute setting ("*x") so specifying one will affect
           both; LESSUTFBINFMT is read after LESSBINFMT so its setting, if
           any, will have priority.  Problematic octets in a UTF-8 file
           (octets of a truncated sequence, octets of a complete but non-
           shortest form sequence, invalid octets, and stray trailing octets)
           are displayed individually using LESSBINFMT so as to facilitate
           diagnostic of how the UTF-8 file is ill-formed.
    
           When the character set is utf-8, in rare cases it may be desirable
           to override the Unicode definition of the type of certain
           characters.  For example, characters in a Private Use Area are
           normally treated as control characters, but if you are using a
           custom font with printable characters in that range, it may be
           desirable to tell **less** to treat such characters as printable.
           This can be done by setting the LESSUTFCHARDEF environment
           variable to a comma-separated list of _character type_ definitions.
           Each character type definition consists of either one hexadecimal
           codepoint or a pair of codepoints separated by a dash, followed by
           a colon and a type character.  Each hexadecimal codepoint may
           optionally be preceded by a "U" or "U+".  If a pair of codepoints
           is given, the type is set for all characters inclusively between
           the two values.  If there are multiple comma-separated codepoint
           values, they must be in ascending numerical order.  The type
           character may be one of:
    
                  p      A normal printable character.
    
                  w      A wide (2-space) printable character.
    
                  b      A binary (non-printable) character.
    
                  c      A composing (zero width) character.
    
           For example, setting LESSUTFCHARDEF to
    
                E000-F8FF:p,F0000-FFFFD:p,100000-10FFFD:p
    
           would make all Private Use Area characters be treated as
           printable.
    


## PROMPTS



           The -P option allows you to tailor the prompt to your preference.
           The string given to the -P option replaces the specified prompt
           string.  Certain characters in the string are interpreted
           specially.  The prompt mechanism is rather complicated to provide
           flexibility, but the ordinary user need not understand the details
           of constructing personalized prompt strings.
    
           A percent sign followed by a single character is expanded
           according to what the following character is.  (References to the
           input file size below refer to the preprocessed size, if an input
           preprocessor is being used.)
    
           %b _X_    Replaced by the byte offset into the current input file.
                  The b is followed by a single character (shown as _X_ above)
                  which specifies the line whose byte offset is to be used.
                  If the character is a "t", the byte offset of the top line
                  in the display is used, an "m" means use the middle line, a
                  "b" means use the bottom line, a "B" means use the line
                  just after the bottom line, and a "j" means use the
                  "target" line, as specified by the -j option.
    
           %B     Replaced by the size of the current input file.
    
           %c     Replaced by the column number of the text appearing in the
                  first column of the screen.
    
           %d _X_    Replaced by the page number of a line in the input file.
                  The line to be used is determined by the _X_ , as with the %b
                  option.
    
           %D     Replaced by the number of pages in the input file, or
                  equivalently, the page number of the last line in the input
                  file.
    
           %E     Replaced by the name of the editor (from the VISUAL
                  environment variable, or the EDITOR environment variable if
                  VISUAL is not defined).  See the discussion of the LESSEDIT
                  feature below.
    
           %f     Replaced by the name of the current input file.
    
           %F     Replaced by the last component of the name of the current
                  input file.
    
           %g     Replaced by the shell-escaped name of the current input
                  file.  This is useful when the expanded string will be used
                  in a shell command, such as in LESSEDIT.
    
           %i     Replaced by the index of the current file in the list of
                  input files.
    
           %l _X_    Replaced by the line number of a line in the input file.
                  The line to be used is determined by the _X_ , as with the %b
                  option.
    
           %L     Replaced by the line number of the last line in the input
                  file.
    
           %m     Replaced by the total number of input files.
    
           %o     Replaced by the URI of the currently selected OSC 8
                  hyperlink, or a question mark if no hyperlink is selected.
                  This is used by OSC 8 handlers as explained in the ^O^O
                  command description.
    
           %p _X_    Replaced by the percent into the current input file, based
                  on byte offsets.  The line used is determined by the _X_ as
                  with the %b option.
    
           %P _X_    Replaced by the percent into the current input file, based
                  on line numbers.  The line used is determined by the _X_ as
                  with the %b option.
    
           %s     Same as %B.
    
           %t     Causes any trailing spaces to be removed.  Usually used at
                  the end of the string, but may appear anywhere.
    
           %T     Normally expands to the word "file".  However if viewing
                  files via a tags list using the -t option, it expands to
                  the word "tag".
    
           %x     Replaced by the name of the next input file in the list.
    
           If any item is unknown (for example, the file size if input is a
           pipe), a question mark is printed instead.
    
           The format of the prompt string can be changed depending on
           certain conditions.  A question mark followed by a single
           character acts like an "IF": depending on the following character,
           a condition is evaluated.  If the condition is true, any
           characters following the question mark and condition character, up
           to a period, are included in the prompt.  If the condition is
           false, such characters are not included.  A colon appearing
           between the question mark and the period can be used to establish
           an "ELSE": any characters between the colon and the period are
           included in the string if and only if the IF condition is false.
           Condition characters (which follow a question mark) may be:
    
           ?a     True if any characters have been included in the prompt so
                  far.
    
           ?b _X_    True if the byte offset of the specified line is known.
    
           ?B     True if the size of current input file is known.
    
           ?c     True if the text is horizontally shifted (%c is not zero).
    
           ?d _X_    True if the page number of the specified line is known.
    
           ?e     True if at end-of-file.
    
           ?f     True if there is an input filename (that is, if input is
                  not a pipe).
    
           ?l _X_    True if the line number of the specified line is known.
    
           ?L     True if the line number of the last line in the file is
                  known.
    
           ?m     True if there is more than one input file.
    
           ?n     True if this is the first prompt in a new input file.
    
           ?p _X_    True if the percent into the current input file, based on
                  byte offsets, of the specified line is known.
    
           ?P _X_    True if the percent into the current input file, based on
                  line numbers, of the specified line is known.
    
           ?s     Same as "?B".
    
           ?x     True if there is a next input file (that is, if the current
                  input file is not the last one).
    
           Any characters other than the special ones (question mark, colon,
           period, percent, and backslash) become literally part of the
           prompt.  Any of the special characters may be included in the
           prompt literally by preceding it with a backslash.
    
           Some examples:
    
           ?f%f:Standard input.
    
           This prompt prints the filename, if known; otherwise the string
           "Standard input".
    
           ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...
    
           This prompt would print the filename, if known.  The filename is
           followed by the line number, if known, otherwise the percent if
           known, otherwise the byte offset if known.  Otherwise, a dash is
           printed.  Notice how each question mark has a matching period, and
           how the % after the %pt is included literally by escaping it with
           a backslash.
    
           ?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\: %x..%t
    
           This prints the filename if this is the first prompt in a file,
           followed by the "file N of N" message if there is more than one
           input file.  Then, if we are at end-of-file, the string "(END)" is
           printed followed by the name of the next file, if there is one.
           Finally, any trailing spaces are truncated.  This is the default
           prompt.  For reference, here are the defaults for the other two
           prompts (-m and -M respectively).  Each is broken into two lines
           here for readability only.
    
           ?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\: %x.:
                ?pB%pB\%:byte %bB?s/%s...%t
    
           ?f%f .?n?m(%T %i of %m) ..?ltlines %lt-%lb?L/%L. :
                byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t
    
           And here is the default message produced by the = command:
    
           ?f%f .?m(%T %i of %m) .?ltlines %lt-%lb?L/%L. .
                byte %bB?s/%s. ?e(END) :?pB%pB\%..%t
    
           The prompt expansion features are also used for another purpose:
           if an environment variable LESSEDIT is defined, it is used as the
           command to be executed when the v command is invoked.  The
           LESSEDIT string is expanded in the same way as the prompt strings.
           The default value for LESSEDIT is:
    
                %E ?lm+%lm. %g
    
           Note that this expands to the editor name, followed by a + and the
           line number, followed by the shell-escaped file name.  If your
           editor does not accept the "+linenumber" syntax, or has other
           differences in invocation syntax, the LESSEDIT variable can be
           changed to modify this default.
    


## SECURITY



           When the environment variable LESSSECURE is set to 1, **less** runs in
           a "secure" mode.  In this mode, these features are disabled:
    
           edit      the edit command (v)
    
           examine   the examine command (:e)
    
           glob      metacharacters such as * in filenames,
                     and filename completion (TAB, ^L)
    
           history   history file
    
           lesskey   use of lesskey files (-k and --lesskey-src)
    
           lessopen  input preprocessor (LESSOPEN environment variable)
    
           logfile   log files (s and -o)
    
           osc8      opening OSC 8 links (^O^O)
    
           pipe      the pipe command (|)
    
           shell     the shell and pshell commands (! and #)
    
           stop      stopping **less** via a SIGTSTP signal
    
           tags      use of tags files (-t)
    
           The LESSSECURE_ALLOW environment variable can be set to a comma-
           separated list of names of features which are selectively enabled
           when LESSSECURE is set.  Each feature name is the first word in
           each line in the above list.  A feature name may be abbreviated as
           long as the abbreviation is unambiguous.  For example, if
           LESSSECURE=1 and LESSSECURE_ALLOW=hist,edit were set, all of the
           above features would be disabled except for history files and the
           edit command.
    
           Less can also be compiled to be permanently in "secure" mode.  In
           that case, the LESSSECURE and LESSSECURE_ALLOW variables are ig‐
           nored.
    


## COMPATIBILITY WITH MORE



           If the environment variable LESS_IS_MORE is set to 1, or if the
           program is invoked via a file link named "more" and the environ‐
           ment variable LESS_IS_MORE is not set to 0, **less** behaves (mostly)
           in conformance with the POSIX more(1) command specification.  In
           this mode, less behaves differently in these ways:
    
           The -e option works differently.  If the -e option is not set,
           **less** behaves as if the -e option were set.  If the -e option is
           set, **less** behaves as if the -E option were set.
    
           The -m option works differently.  If the -m option is not set, the
           medium prompt is used, and it is prefixed with the string
           "--More--".  If the -m option is set, the short prompt is used.
    
           The -n option acts like the -z option.  The normal behavior of the
           -n option is unavailable in this mode.
    
           The parameter to the -p option is taken to be a **less** command
           rather than a search pattern.
    
           The LESS environment variable is ignored, and the MORE environment
           variable is used in its place.
    


## ENVIRONMENT VARIABLES



           Environment variables may be specified either in the system envi‐
           ronment as usual, or in a lesskey(1) file.  If environment vari‐
           ables are defined in more than one place, variables defined in a
           local lesskey file take precedence over variables defined in the
           system environment, which take precedence over variables defined
           in the system-wide lesskey file.
    
           COLUMNS
                  Sets the number of columns on the screen.  Takes precedence
                  over the number of columns specified by the TERM variable.
                  (But if you have a windowing system which supports TIOCG‐
                  WINSZ or WIOCGETD, the window system's idea of the screen
                  size takes precedence over the LINES and COLUMNS environ‐
                  ment variables.)
    
           EDITOR The name of the editor (used for the v command).
    
           HOME   Name of the user's home directory (used to find a lesskey
                  file on Unix and OS/2 systems).
    
           HOMEDRIVE, HOMEPATH
                  Concatenation of the HOMEDRIVE and HOMEPATH environment
                  variables is the name of the user's home directory if the
                  HOME variable is not set (only in the Windows version).
    
           INIT   Name of the user's init directory (used to find a lesskey
                  file on OS/2 systems).
    
           LANG   Language for determining the character set.
    
           LC_CTYPE
                  Language for determining the character set.
    
           LESS   Options which are passed to **less** automatically.
    
           LESSANSIENDCHARS
                  Characters which may end an ANSI color escape sequence (de‐
                  fault "m").
    
           LESSANSIMIDCHARS
                  Characters which may appear between the ESC character and
                  the end character in an ANSI color escape sequence (default
                  "0123456789:;[?!"'#%()*+ ").
    
           LESSANSIOSCALLOW
                  A comma-separated list of OSC types which are output di‐
                  rectly to the terminal when -R is in effect.  By default,
                  only OSC 8 sequences are output directly.
    
           LESSANSIOSCCHARS
                  Characters which may follow an ESC character to mark the
                  start of an "OS Command" sequence.  All characters that
                  follow this character up to a String Terminator (ESC-back‐
                  slash or BEL) are considered to be part of the OSC sequence
                  (default "]").  If a character in LESSANSIOSCCHARS is fol‐
                  lowed by an asterisk, sequences that begin with that char‐
                  acter in the file contents are passed through to the termi‐
                  nal; otherwise only sequences that appear in a prompt
                  string are passed through.
    
           LESSBINFMT
                  Format for displaying non-printable, non-control charac‐
                  ters.
    
           LESSCHARDEF
                  Defines a character set.
    
           LESSCHARSET
                  Selects a predefined character set.
    
           LESSCLOSE
                  Command line to invoke the (optional) input-postprocessor.
    
           LESSECHO
                  Name of the lessecho program (default "lessecho").  The
                  lessecho program is needed to expand metacharacters, such
                  as * and ?, in filenames on Unix systems.
    
           LESSEDIT
                  Editor prototype string (used for the v command).  See dis‐
                  cussion under PROMPTS.
    
           LESSGLOBALTAGS
                  Name of the command used by the -t option to find global
                  tags.  Normally should be set to "global" if your system
                  has the **global**(1) command.  If not set, global tags are not
                  used.
    
           LESSHISTFILE
                  Name of the history file used to remember search commands
                  and shell commands between invocations of **less**.  If set to
                  "-" or "/dev/null", a history file is not used.  The de‐
                  fault depends on the operating system, but is usually:
    
                  Linux and Unix
                         "$XDG_STATE_HOME/lesshst" or "$HOME/.lo‐
                         cal/state/lesshst" or "$XDG_DATA_HOME/lesshst" or
                         "$HOME/.lesshst".
    
                  Windows and MS-DOS
                         "$HOME/_lesshst".
    
                  OS/2   "$HOME/lesshst.ini" or "$INIT/lesshst.ini".
    
           LESSHISTSIZE
                  The maximum number of commands to save in the history file.
                  The default is 100.
    
           LESSKEYIN
                  Name of the default _lesskey source_ file.
    
           LESSKEY
                  Name of the default _lesskey binary_ file. (Not used if
                  "$LESSKEYIN" exists.)
    
           LESSKEY_CONTENT
                  The value is parsed as if it were the parameter of a
                  --lesskey-content option.
    
           LESSKEYIN_SYSTEM
                  Name of the default system-wide _lesskey source_ file.
    
           LESSKEY_SYSTEM
                  Name of the default system-wide _lesskey binary_ file. (Not
                  used if "$LESSKEYIN_SYSTEM" exists.)
    
           LESSMETACHARS
                  List of characters which are considered "metacharacters" by
                  the shell.
    
           LESSMETAESCAPE
                  Prefix which less will add before each metacharacter in a
                  command sent to the shell.  If LESSMETAESCAPE is an empty
                  string, commands containing metacharacters will not be
                  passed to the shell.
    
           LESSOPEN
                  Command line to invoke the (optional) input-preprocessor.
    
           LESSSECURE
                  Runs less in "secure" mode.  See discussion under SECURITY.
    
           LESSSECURE_ALLOW
                  Enables individual features which are normally disabled by
                  LESSSECURE.  See discussion under SECURITY.
    
           LESSSEPARATOR
                  String to be appended to a directory name in filename com‐
                  pletion.
    
           LESSUTFBINFMT
                  Format for displaying non-printable Unicode code points.
    
           LESSUTFCHARDEF
                  Overrides the type of specified Unicode characters.
    
           LESS_COLUMNS
                  Sets the number of columns on the screen.  Unlike COLUMNS,
                  takes precedence over the system's idea of the screen size,
                  so it can be used to make **less** use less than the full
                  screen width.  If set to a negative number, sets the number
                  of columns used to this much less than the actual screen
                  width.
    
           LESS_LINES
                  Sets the number of lines on the screen.  Unlike LINES,
                  takes precedence over the system's idea of the screen size,
                  so it can be used to make **less** use less than the full
                  screen height.  If set to a negative number, sets the num‐
                  ber of lines used to this much less than the actual screen
                  height.  When set, **less** repaints the entire screen on every
                  movement command, so scrolling may be slower.
    
           LESS_DATA_DELAY
                  Duration (in milliseconds) after starting to read data from
                  the input, after which the "Waiting for data" message will
                  be displayed.  The default is 4000 (4 seconds).
    
           LESS_IS_MORE
                  Emulate the more(1) command.
    
           LESS_OSC8_xxx
                  Where "xxx" is a URI scheme such as "http" or "file", sets
                  an OSC 8 handler for opening OSC 8 links containing a URI
                  with that scheme.
    
           LESS_OSC8_ANY
                  Sets an OSC 8 handler for opening OSC 8 links for which
                  there is no specific LESS_OSC8_xxx handler set for the
                  "xxx" scheme.
    
           LESS_SHELL_LINES
                  When the -F option is set, **less** exits automatically if the
                  number of screen lines used to display the file is less
                  than or equal to the screen height minus the value of the
                  LESS_SHELL_LINES variable.  Thus, if you use a shell prompt
                  which occupies more than one screen line, this variable can
                  be set to the number of lines used by your prompt, to en‐
                  sure that the entire file can be seen when -F is used.  If
                  not set, LESS_SHELL_LINES is assumed to be 1.
    
           LESS_SIGUSR1
                  If set to a string of one or more **less** command characters,
                  those commands will be executed when **less** receives a SI‐
                  GUSR1 signal.
    
           LESS_TERMCAP_xx
                  Where "xx" is any two characters, overrides the definition
                  of the termcap "xx" capability for the terminal.
    
           LESS_UNSUPPORT
                  A space-separated list of command line options.  These op‐
                  tions will be ignored (with no error message) if they ap‐
                  pear on the command line or in the LESS environment vari‐
                  able.  Options listed in LESS_UNSUPPORT can still be
                  changed by the - and -- commands.  Each option in LESS_UN‐
                  SUPPORT is a dash followed by a single character option
                  letter, or two dashes followed by a long option name.
    
           LINES  Sets the number of lines on the screen.  Takes precedence
                  over the number of lines specified by the TERM variable.
                  (But if you have a windowing system which supports TIOCG‐
                  WINSZ or WIOCGETD, the window system's idea of the screen
                  size takes precedence over the LINES and COLUMNS environ‐
                  ment variables.)
    
           MORE   Options which are passed to **less** automatically when running
                  in **more** -compatible mode.
    
           PATH   User's search path (used to find a lesskey file on MS-DOS,
                  Windows, and OS/2 systems).
    
           SHELL  The shell used to execute the ! command, as well as to ex‐
                  pand filenames.
    
           TERM   The type of terminal on which **less** is being run.
    
           VISUAL The name of the editor (used for the v command).
    
           XDG_CONFIG_HOME
                  Possible location of the **lesskey** file; see the KEY BINDINGS
                  section.
    
           XDG_DATA_HOME
                  Possible location of the history file; see the description
                  of the LESSHISTFILE environment variable.
    
           XDG_STATE_HOME
                  Possible location of the history file; see the description
                  of the LESSHISTFILE environment variable.
    


* * *