The following variables are used by the shell: CDPATH The search path for the cd command. COLUMNS If this variable is set, the value is used to define the width of the edit window for the shell edit modes and for printing select lists. EDITOR If the VISUAL variable is not set, the value of this variable will be checked for the patterns as described with VISUAL below and the corresponding editing option (see Special Command set below) will be turned on. ENV    If this variable is set, then parameter expansion, command substitution, and arithmetic substitution are performed on the value to generate the pathname of the script that will be executed when the shell is invoked interactively (see Invocation below).  This file is typically used for alias and function definitions.  The default value is $HOME/.kshrc.  On systems that support a system wide /etc/ksh.kshrc initialization file, if the filename generated by the expansion of ENV begins with /./ or ././ the system wide initialization file will not be executed. FCEDIT Obsolete name for the default editor name for the hist command.  FCEDIT is not used when HISTEDIT is set. FIGNORE A pattern that defines the set of filenames that will be ignored when performing filename matching. FPATH  The search path for function definitions.  The directories in this path are searched for a file with the same name as the function or command when a function with the -u attribute is referenced and when a command is not found. If an executable file with the name of that command is found, then it is read and executed in the current environment.  Unlike PATH, the current directory must be represented explicitly by .  rather than by adjacent : characters or a beginning or ending :. HISTCMD Number of the current command in the history file. HISTEDIT Name for the default editor name for the hist command. HISTFILE If this variable is set when the shell is invoked, then the value is the pathname of the file that will be used to store the command history (see Command Re-entry below). HISTSIZE If this variable is set when the shell is invoked, then the number of previously entered commands that are accessible by this shell will be greater than or equal to this number. The default is 512. HOME   The default argument (home directory) for the cd command. IFS    Internal field separators, normally space, tab, and new- line that are used to separate the results of command substitution or parameter expansion and to separate fields with the built-in command read.  The first character of the IFS variable is used to separate arguments for the "$*" substitution (see Quoting below).  Each single occurrence of an IFS character in the string to be split, that is not in the isspace character class, and any adjacent characters in IFS that are in the isspace character class, delimit a field.  One or more characters in IFS that belong to the isspace character class, delimit a field.  In addition, if the same isspace character appears consecutively inside IFS, this character is treated as if it were not in the isspace class, so that if IFS consists of two tab characters, then two adjacent tab characters delimit a null field. JOBMAX This variable defines the maximum number running background jobs that can run at a time.  When this limit is reached, the shell will wait for a job to complete before staring a new job. LANG   This variable determines the locale category for any category not specifically selected with a variable starting with LC_ or LANG. LC_ALL This variable overrides the value of the LANG variable and any other LC_ variable. LC_COLLATE This variable determines the locale category for character collation information. LC_CTYPE This variable determines the locale category for character handling functions.  It determines the character classes for pattern matching (see File Name Generation below). LC_NUMERIC This variable determines the locale category for the decimal point character. LINES  If this variable is set, the value is used to determine the column length for printing select lists.  Select lists will print vertically until about two-thirds of LINES lines are filled. MAIL   If this variable is set to the name of a mail file and the MAILPATH variable is not set, then the shell informs the user of arrival of mail in the specified file. MAILCHECK This variable specifies how often (in seconds) the shell will check for changes in the modification time of any of the files specified by the MAILPATH or MAIL variables.  The default value is 600 seconds.  When the time has elapsed the shell will check before issuing the next prompt. MAILPATH A colon ( : ) separated list of file names.  If this variable is set, then the shell informs the user of any modifications to the specified files that have occurred within the last MAILCHECK seconds.  Each file name can be followed by a ?  and a message that will be printed.  The message will undergo parameter expansion, command substitution, and arithmetic substitution with the variable $_ defined as the name of the file that has changed.  The default message is you have mail in $_. PATH   The search path for commands (see Execution below).  The user may not change PATH if executing under rksh (except in .profile). PS1    The value of this variable is expanded for parameter expansion, command substitution, and arithmetic substitution to define the primary prompt string which by default is ``$ ''.  The character !  in the primary prompt string is replaced by the command number (see Command Re- entry below).  Two successive occurrences of !  will produce a single !  when the prompt string is printed. PS2    Secondary prompt string, by default ``> ''. PS3    Selection prompt string used within a select loop, by default ``#? ''. PS4    The value of this variable is expanded for parameter evaluation, command substitution, and arithmetic substitution and precedes each line of an execution trace. By default, PS4 is ``+ ''.  In addition when PS4 is unset, the execution trace prompt is also ``+ ''. SH_OPTIONS The value consists of blank separated name=value words. For each name that is the name of a known option the variable .sh.opt_name is assigned value.  Currently the only valid option name is astbin. SHELL  The pathname of the shell is kept in the environment.  At invocation, if the basename of this variable is rsh, rksh, or krsh, then the shell becomes restricted.  If it is pfsh or pfksh, then the shell becomes a profile shell (see pfexec(1)). TIMEFORMAT The value of this parameter is used as a format string specifying how the timing information for pipelines prefixed with the time reserved word should be displayed. The % character introduces a format sequence that is expanded to a time value or other information.  The format sequences and their meanings are as follows. %%        A literal %. %[p][l]R  The elapsed time in seconds. %[p][l]U  The number of CPU seconds spent in user mode. %[p][l]S  The number of CPU seconds spent in system mode. %[p][l]C  The total number of CPU seconds; i.e., the sum of the time spent in user plus system mode. %P        The CPU percentage (i.e., CPU utilization), computed as C / R.