[SOLVED] Installing "which" on Ubuntu 18.04.4

Bill_Blessing · 04-15-2020, 02:45 PM

Googling for the "which" program is not exactly easy, as the ubiquity of the program name defeats search. sudo apt-get install which doesn't work out of the gate, so I was wondering if someone knew which repository which is found in (confusing?), or if I have to download it and compile from the source.

which is needed for me to get Buildroot set up.

ehartman · 04-15-2020, 03:16 PM

Quote:

Originally Posted by Bill_Blessing

Googling for the "which" program is not exactly easy, as the ubiquity of the program name defeats search.

In Slackware it is a package called "which" too:

Quote:

GNU '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). 'Which' is a built-in function in many shells.

The GNU version of which was written by Carlo Wood.

(from the description of the package)
You can find the source on ftp.gnu.org/gnu/which. The latest version is 2.21, which is already 5 years old.

But as it already tells you, in some shells (not bash, as far as I know) it is a built-in, so not an external program. In tchs it IS:

Quote:

which command (+)
Displays the command that will be executed by the shell after substitutions, path searching, etc. The builtin command is just like which(1), but it correctly reports tcsh aliases and builtins and is 10 to 100 times faster.

(from the man page for tcsh)

Bill_Blessing · 04-15-2020, 03:36 PM

Now I feel dumb. When I ran sudo apt-cache policy which, it said it wasn't installed. I just tried it: which ping, and the result was the as-expected /bin/ping. Thank you!

cement_head · 02-05-2022, 06:54 AM

Quote:

Originally Posted by Bill_Blessing

Now I feel dumb. When I ran sudo apt-cache policy which, it said it wasn't installed. I just tried it: which ping, and the result was the as-expected /bin/ping. Thank you!

Don't! I just did the same thing - I guess it got folded into BASH at some point.

shruggy · 02-05-2022, 08:27 AM

which on Debian (excluding the version currently in sid) and Ubuntu (excluding not yet released Jammy) is a Debian-specific shell script provided by package debianutils. It was recently deprecated, and now is managed through Debian Alternatives System, so it could be GNU which, or FreeBSD which, or still the old Debian which.

Possible alternatives are listed in the comments to the bug report linked above:

type in any POSIX-compatible shell
command -v in any POSIX-compatible shell
whereis from util-linux
the which builtin in tcsh, zsh
the whence builtin in ksh and its clones
the which() function in /var/lib/dpkg/info/keyboard-configuration.postinst
etc.