Table A-5 shows a complete list of environment variables available in bash 3.0. The letters in the Type column of the table have the following meanings: A = Array, L = colon-separated list, R = read-only, U = unsetting it causes it to lose its special meaning.
Note that the variables beginning
BASH_ and beginning
COMP, as well as the variables
DIRSTACK, FUNCNAME, GLOBIGNORE, GROUPS, HISTIGNORE,
HOSTNAME, HISTTIMEFORMAT, LANG, LC_ALL, LC_COLLATE, LC_MESSAGE,
MACHTYPE, PIPESTATUS, SHELLOPTS, and
TIMEFORMAT are not available in versions prior
ENV found in earlier versions.
Table A-5. Built-in shell environment variables
A single string containing the positional
parameters given to the current script or function, separated by
the first character of
Each of the positional parameters given to the
current script or function, given as a list of double-quoted
The number of arguments given to the current script or function.
Options given to the shell on invocation.
Exit status of the previous command.
Last argument to the previous command.
Process ID of the shell process.
Process ID of the last background command.
Name of the shell or shell script.
The full pathname used to invoke this instance of bash.
An array of values, which are the number of parameters in each frame of the current bash execution call stack. The number of parameters ...