Built-in shell variables

# Number of arguments given to current process.

@ Command-line arguments to current process. Inside double quotes, expands to individual arguments.

* Command-line arguments to current process. Inside double quotes, expands to a single argument.

- (hyphen) Options given to shell on invocation.

? Exit status of previous command.

$ Process ID of shell process.

0 (zero) The name of the shell program.

! Process ID of last background command. Use this to save process ID numbers for later use with the wait

command.

ENV Used only by interactive shells upon invocation; the value of$ENV is parameter-expanded. The result

should be a full pathname for a file to be read and executed at startup. This is an XSI requirement.

HOME Home (login) directory.

IFS Internal field separator; i.e., the list of characters that act as word separators. Normally set to space, tab,

and newline.

LANG Default name of current locale; overridden by the otherLC_* variables.

LC_ALL Name of current locale; overrides LANG and the otherLC_* variables.

LC_COLLATE Name of current locale for character collation (sorting) purposes.