1:which

From Linux Man Pages

      which - shows the full path of (shell) commands.
      
      which [options] [--] programname [...]

Contents 1 DESCRIPTION 2 OPTIONS 3 RETURN VALUE 4 EXAMPLE 5 BUGS 6 RELATED 7 CATEGORY

DESCRIPTION

      Which takes one or more arguments. For each of its arguments it prints to stdout the full path of the executables
      that would have been executed when this argument had been entered at the shell prompt. It does this by searching
      for an executable or script in the directories listed in the 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 on stdout. This is useful in combination with using an alias
          for which itself. For example
          alias which=?alias | which -i?.
 
      --skip-alias
          Ignore option `--read-alias?, if any. This is useful to explicity search for normal binaries, while using the
          `--read-alias? option in an alias or function for which.
 
      --read-functions
          Read shell function definitions from stdin, reporting matching ones on stdout. This is useful in combination
          with using a shell function 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 to explicity search for normal binaries, while using
          the `--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 and executables which reside in the HOME directory.
 
      --show-dot
          If a directory in PATH starts with a dot and a matching executable was found for that path, then print
          "./programname" rather than the full path.
 
      --show-tilde
          Output a tilde when a directory matches the HOME directory. This option is ignored when which is invoked as
          root.
 
      --tty-only
          Stop processing options on the right if not on tty.
 
      --version,-v,-V
          Print version information on standard output then exit successfully.
 
      --help
          Print usage information on standard output then exit successfully.

RETURN VALUE

      Which returns the number of failed arguments, or -1 when no `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 which from your prompt, while still printing the full path
      when used from a script:
 
           > which q2
           ~/bin/q2
           > echo `which q2`
           /home/carlo/bin/q2

BUGS

      The HOME directory is determined by looking for the HOME environment variable, which aborts  when  this  variable
      doesn?t  exist.   Which will consider two equivalent directories to be different when one of them contains a path
      with a symbolic link.

RELATED

      bash(1)

CATEGORY