which - shows the full path of (shell) commands

NAME

which - shows the full path of (shell) commands.

SYNOPSIS

which[options] [--] programname [...]

DESCRIPTION

Which takes one or more arguments. For each of its argumentsit prints to stdout the full path of the executablesthat would have been executed when this argument had beenentered at the shell prompt. It does this by searchingfor an executable or script in the directories listed inthe environment variable PATH using the same algorithm as bash(1).

This man page is generated from the file which.texinfo.

OPTIONS

--all, -a: Print all matching executables in PATH, not just the first.
--read-alias, -i: Read aliases from stdin, reporting matching ones onstdout. This is useful in combination with using analias for which itself. For example
alias which='alias | which -i'.
--skip-alias: Ignore option `--read-alias', if any. This is useful toexplicity search for normal binaries, while usingthe `--read-alias' option in an alias or function for which.
--read-functions: Read shell function definitions from stdin, reporting matchingones on stdout. This is useful in combination with using a shellfunction for which itself. For example:
which() { declare -f | which --read-functions $@ }
export -f which
--skip-functions: Ignore option `--read-functions', if any. This is useful toexplicity search for normal binaries, while usingthe `--read-functions' option in an alias or function for which.
--skip-dot: Skip directories in PATH that start with a dot.
--skip-tilde: Skip directories in PATH that start with a tilde andexecutables which reside in the HOME directory.
--show-dot: If a directory in PATH starts with a dot and a matchingexecutable was found for that path, then print"./programname" rather than the full path.
--show-tilde: Output a tilde when a directory matches the HOMEdirectory. This option is ignored when which isinvoked as root.
--tty-only: Stop processing options on the right if not on tty.
--version,-v,-V: Print version information on standard output then exitsuccessfully.
--help: Print usage information on standard output then exitsuccessfully.

RETURN VALUE

Which returns the number of failed arguments, or -1 whenno `programname' was given.

EXAMPLE

The recommended way to use this utility is by adding an alias (C shell)or shell function (Bourne shell) for which like the following:

[ba]sh:

which ()
{
  (alias; declare -f) | /usr/bin/which --tty-only --read-alias --read-functions --show-tilde --show-dot $@
}
export -f which

[t]csh:

alias which 'alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'

This will print the readable ~/ and ./ when starting whichfrom your prompt, while still printing the full path whenused from a script:

> which q2
~/bin/q2
> echo `which q2`
/home/carlo/bin/q2

BUGS

The HOME directory is determined by looking for the HOMEenvironment variable, which aborts when this variabledoesn't exist. Which will consider two equivalent directoriesto be different when one of them contains a pathwith a symbolic link.

AUTHOR

Carlo Wood <carlo@gnu.org>