# tset

## NAME



           **tset** , **reset** - terminal initialization
    


## SYNOPSIS



           **tset**[**-IQVcqrsw**] [**-**] [**-e** _ch_] [**-i** _ch_] [**-k** _ch_] [**-m** _mapping_]
           [_terminal_]
           **reset**[**-IQVcqrsw**] [**-**] [**-e** _ch_] [**-i** _ch_] [**-k** _ch_] [**-m** _mapping_]
           [_terminal_]
    


## DESCRIPTION



       **tset - initialization**
           This program initializes terminals.
    
           First, **tset** retrieves the current terminal mode settings for your
           terminal.  It does this by successively testing
    
           •   the standard error,
    
           •   standard output,
    
           •   standard input and
    
           •   ultimately “/dev/tty”
    
           to obtain terminal settings.  Having retrieved these settings,
           **tset** remembers which file descriptor to use when updating
           settings.
    
           Next, **tset** determines the type of terminal that you are using.
           This determination is done as follows, using the first terminal
           type found.
    
           1. The **terminal** argument specified on the command line.
    
           2. The value of the **TERM** environmental variable.
    
           3. (BSD systems only.) The terminal type associated with the
           standard error output device in the _/etc/ttys_ file.  (On System-V-
           like UNIXes and systems using that convention, **getty**(1) does this
           job by setting **TERM** according to the type passed to it by
           _/etc/inittab_.)
    
           4. The default terminal type, “unknown”.
    
           If the terminal type was not specified on the command-line, the **-m**
           option mappings are then applied (see the section **TERMINAL TYPE**
           **MAPPING** for more information).  Then, if the terminal type begins
           with a question mark (“?”), the user is prompted for confirmation
           of the terminal type.  An empty response confirms the type, or,
           another type can be entered to specify a new type.  Once the
           terminal type has been determined, the terminal description for
           the terminal is retrieved.  If no terminal description is found
           for the type, the user is prompted for another terminal type.
    
           Once the terminal description is retrieved,
    
           •   if the “**-w** ” option is enabled, **tset** may update the terminal's
               window size.
    
               If the window size cannot be obtained from the operating
               system, but the terminal description (or environment, e.g.,
               **LINES** and **COLUMNS** variables specify this), use this to set the
               operating system's notion of the window size.
    
           •   if the “**-c** ” option is enabled, the backspace, interrupt and
               line kill characters (among many other things) are set
    
           •   unless the “**-I** ” option is enabled, the terminal and tab
               _initialization_ strings are sent to the standard error output,
               and **tset** waits one second (in case a hardware reset was
               issued).
    
           •   Finally, if the erase, interrupt and line kill characters have
               changed, or are not set to their default values, their values
               are displayed to the standard error output.
    
       **reset - reinitialization**
           When invoked as **reset** , **tset** sets the terminal modes to “sane”
           values:
    
           •   sets cooked and echo modes,
    
           •   turns off cbreak and raw modes,
    
           •   turns on newline translation and
    
           •   resets any unset special characters to their default values
    
           before doing the terminal initialization described above.  Also,
           rather than using the terminal _initialization_ strings, it uses the
           terminal _reset_ strings.
    
           The **reset** command is useful after a program dies leaving a
           terminal in an abnormal state:
    
           •   you may have to type
    
                   _< LF>_**reset** _< LF>_
    
               (the line-feed character is normally control-J) to get the
               terminal to work, as carriage-return may no longer work in the
               abnormal state.
    
           •   Also, the terminal will often not echo the command.
    


## OPTIONS



           The options are as follows:
    
           **-c** Set control characters and modes.
    
           **-e** _ch_
                Set the erase character to _ch_.
    
           **-I** Do not send the terminal or tab initialization strings to the
                terminal.
    
           **-i** _ch_
                Set the interrupt character to _ch_.
    
           **-k** _ch_
                Set the line kill character to _ch_.
    
           **-m** _mapping_
                Specify a mapping from a port type to a terminal.  See the
                section **TERMINAL TYPE MAPPING** for more information.
    
           **-Q** Do not display any values for the erase, interrupt and line
                kill characters.  Normally **tset** displays the values for
                control characters which differ from the system's default
                values.
    
           **-q** The terminal type is displayed to the standard output, and
                the terminal is not initialized in any way.  The option “-”
                by itself is equivalent but archaic.
    
           **-r** Print the terminal type to the standard error output.
    
           **-s** Print the sequence of shell commands to initialize the
                environment variable **TERM** to the standard output.  See the
                section **SETTING THE ENVIRONMENT** for details.
    
           **-V** reports the version of ncurses which was used in this
                program, and exits.
    
           **-w** Resize the window to match the size deduced via
                **setupterm**(3X).  Normally this has no effect, unless **setupterm**
                is not able to detect the window size.
    
           The arguments for the **-e** , **-i** , and **-k** options may either be entered
           as actual characters or by using the “hat” notation, i.e.,
           control-h may be specified as “^H” or “^h”.
    
           If neither **-c** or **-w** is given, both options are assumed.
    


## SETTING THE ENVIRONMENT



           It is often desirable to enter the terminal type and information
           about the terminal's capabilities into the shell's environment.
           This is done using the **-s** option.
    
           When the **-s** option is specified, the commands to enter the
           information into the shell's environment are written to the
           standard output.  If the **SHELL** environmental variable ends in
           “csh”, the commands are for **csh** , otherwise, they are for **sh**(1).
           Note, the **csh** commands set and unset the shell variable **noglob** ,
           leaving it unset.  The following line in the **.login** or **.profile**
           files will initialize the environment correctly:
    
               eval `tset -s options ... `
    


## TERMINAL TYPE MAPPING



           When the terminal is not hardwired into the system (or the current
           system information is incorrect) the terminal type derived from
           the _/etc/ttys_ file or the **TERM** environmental variable is often
           something generic like **network** , **dialup** , or **unknown**.  When **tset** is
           used in a startup script it is often desirable to provide
           information about the type of terminal used on such ports.
    
           The **-m** options maps from some set of conditions to a terminal
           type, that is, to tell **tset** “If I'm on this port at a particular
           speed, guess that I'm on that kind of terminal”.
    
           The argument to the **-m** option consists of an optional port type,
           an optional operator, an optional baud rate specification, an
           optional colon (“:”) character and a terminal type.  The port type
           is a string (delimited by either the operator or the colon
           character).  The operator may be any combination of “>”, “<”, “@”,
           and “!”; “>” means greater than, “<” means less than, “@” means
           equal to and “!” inverts the sense of the test.  The baud rate is
           specified as a number and is compared with the speed of the
           standard error output (which should be the control terminal).  The
           terminal type is a string.
    
           If the terminal type is not specified on the command line, the **-m**
           mappings are applied to the terminal type.  If the port type and
           baud rate match the mapping, the terminal type specified in the
           mapping replaces the current type.  If more than one mapping is
           specified, the first applicable mapping is used.
    
           For example, consider the following mapping: **dialup >9600:vt100**.
           The port type is dialup , the operator is >, the baud rate
           specification is 9600, and the terminal type is vt100.  The result
           of this mapping is to specify that if the terminal type is **dialup** ,
           and the baud rate is greater than 9600 baud, a terminal type of
           **vt100** will be used.
    
           If no baud rate is specified, the terminal type will match any
           baud rate.  If no port type is specified, the terminal type will
           match any port type.  For example, **-m dialup:vt100 -m :?xterm** will
           cause any dialup port, regardless of baud rate, to match the
           terminal type vt100, and any non-dialup port type to match the
           terminal type ?xterm.  Note, because of the leading question mark,
           the user will be queried on a default port as to whether they are
           actually using an xterm terminal.
    
           No whitespace characters are permitted in the **-m** option argument.
           Also, to avoid problems with meta-characters, it is suggested that
           the entire **-m** option argument be placed within single quote
           characters, and that **csh** users insert a backslash character (“\”)
           before any exclamation marks (“!”).
    


## COMPATIBILITY



           Neither IEEE Std 1003.1/The Open Group Base Specifications Issue 7
           (POSIX.1-2008) nor X/Open Curses Issue 7 documents **tset** or **reset**.
    
           The AT&T **tput** utility (AIX, HPUX, Solaris) incorporated the
           terminal-mode manipulation as well as termcap-based features such
           as resetting tabstops from **tset** in BSD (4.1c), presumably with the
           intention of making **tset** obsolete.  However, each of those systems
           still provides **tset**.  In fact, the commonly-used **reset** utility is
           always an alias for **tset**.
    
           The **tset** utility provides for backward-compatibility with BSD
           environments (under most modern UNIXes, **/etc/inittab** and **getty**(1)
           can set **TERM** appropriately for each dial-up line; this obviates
           what was **tset** 's most important use).  This implementation behaves
           like 4.4BSD **tset** , with a few exceptions specified here.
    
           A few options are different because the **TERMCAP** variable is no
           longer supported under terminfo-based **ncurses** :
    
           •   The **-S** option of BSD **tset** no longer works; it prints an error
               message to the standard error and dies.
    
           •   The **-s** option only sets **TERM** , not **TERMCAP**.
    
           There was an undocumented 4.4BSD feature that invoking **tset** via a
           link named “TSET” (or via any other name beginning with an upper-
           case letter) set the terminal to use upper-case only.  This
           feature has been omitted.
    
           The **-A** , **-E** , **-h** , **-u** and **-v** options were deleted from the **tset**
           utility in 4.4BSD.  None of them were documented in 4.3BSD and all
           are of limited utility at best.  The **-a** , **-d** , and **-p** options are
           similarly not documented or useful, but were retained as they
           appear to be in widespread use.  It is strongly recommended that
           any usage of these three options be changed to use the **-m** option
           instead.  The **-a** , **-d** , and **-p** options are therefore omitted from
           the usage summary above.
    
           Very old systems, e.g., 3BSD, used a different terminal driver
           which was replaced in 4BSD in the early 1980s.  To accommodate
           these older systems, the 4BSD **tset** provided a **-n** option to specify
           that the new terminal driver should be used.  This implementation
           does not provide that choice.
    
           It is still permissible to specify the **-e** , **-i** , and **-k** options
           without arguments, although it is strongly recommended that such
           usage be fixed to explicitly specify the character.
    
           As of 4.4BSD, executing **tset** as **reset** no longer implies the **-Q**
           option.  Also, the interaction between the - option and the
           _terminal_ argument in some historic implementations of **tset** has
           been removed.
    
           The **-c** and **-w** options are not found in earlier implementations.
           However, a different window size-change feature was provided in
           4.4BSD.
    
           •   In 4.4BSD, **tset** uses the window size from the termcap
               description to set the window size if **tset** is not able to
               obtain the window size from the operating system.
    
           •   In ncurses, **tset** obtains the window size using **setupterm** ,
               which may be from the operating system, the **LINES** and **COLUMNS**
               environment variables or the terminal description.
    
           Obtaining the window size from the terminal description is common
           to both implementations, but considered obsolescent.  Its only
           practical use is for hardware terminals.  Generally speaking, a
           window size would be unset only if there were some problem
           obtaining the value from the operating system (and **setupterm** would
           still fail).  For that reason, the **LINES** and **COLUMNS** environment
           variables may be useful for working around window-size problems.
           Those have the drawback that if the window is resized, those
           variables must be recomputed and reassigned.  To do this more
           easily, use the **resize**(1) program.
    


## ENVIRONMENT



           The **tset** command uses these environment variables:
    
           SHELL
                tells **tset** whether to initialize **TERM** using **sh**(1) or **csh**(1)
                syntax.
    
           TERM Denotes your terminal type.  Each terminal type is distinct,
                though many are similar.
    
           TERMCAP
                may denote the location of a termcap database.  If it is not
                an absolute pathname, e.g., begins with a “/”, **tset** removes
                the variable from the environment before looking for the
                terminal description.
    


## FILES



           /etc/ttys
                system port name to terminal type mapping database (BSD
                versions only).
    
           terminfo
                terminal capability database
    


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