Unix in a Nutshell, 4th Edition

Other Shell Variables

The following variables are not automatically set by the shell, although many of them can influence the shell’s behavior. They are typically used in your .profile file, where you can define them to suit your needs. Variables can be assigned values by issuing commands of the form:

variable=value

This list includes the type of value expected when defining these variables. Those that are specific to the Bash shell are marked as (B). Those that are specific to the Korn shell are marked as (K). Those that are specific to ksh93 are marked (K93).

CDPATH= dirs	Directories searched by cd; allows shortcuts in changing directories; unset by default.
COLUMNS= n	Screen’s column width; used in line edit modes and select lists.
COMPREPLY=( words ... )	(B) Array variable from which Bash reads the possible completions generated by a completion function.
EDITOR= file	(K) Pathname of line edit mode to turn on (can end in emacs or vi); used when VISUAL is not set.
EMACS	(B) If the value starts with t, Bash assumes it’s running in an Emacs buffer and disables line editing.
ENV= file	Name of script that gets executed at start-up; useful for storing alias and function definitions. For example, ENV=$HOME/.kshrc.
FCEDIT= file	Editor used by fc command (default is /bin/ed). Obsoleted in ksh93 by HISTEDIT.
FIGNORE= pattern	(K93) Pattern describing the set of filenames to ignore during pattern matching. (B) Similar: colon-separated list of patterns describing ...