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Why is the command called which and not where?

Logically, you would want to search for the location of the executables, hence "where" are they, but not which.

dr_
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Gotoro
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    Why would you want to search for the location of an executable and not know which of the installed versions of an executable would be called? The location of an executable, if there's only one, is unimportant. If there are several, you want to know which of them would be called, wouldn't you? – Kusalananda Sep 30 '21 at 17:48
  • Does this answer your question? Why not use "which"? What to use then? – Kusalananda Sep 30 '21 at 17:59
  • There is a whence command in Korn shells ;-). – Stephen Kitt Sep 30 '21 at 18:34
  • it is not a search for an executable ... it does not return multiple possibilities – jsotola Sep 30 '21 at 18:36
  • @jsotola it doesn’t by default but it can — which -a. – Stephen Kitt Sep 30 '21 at 18:50
  • Of course I tried searching for the answer myself beforehand, but the post you provided doesn't answer the etymology of the naming at all @they – Gotoro Sep 30 '21 at 18:53
  • You can easily find the etymology and origins of the naming of the "recorder", which would contain at least some sort of explanation, which is not as easy with the "which" command. That's exactly why I asked the question and put a history tag on it - maybe somebody knows, @zevzek – Gotoro Sep 30 '21 at 19:07
  • Perhaps it's because I've been using *nix since forever - but which makes perfect sense to me for the reasons outlined in the first comment - sure, I may want to know where a certain command is, but more importantly, I want to know which command is run if I type xyzzy - since that name could exist in multiple locations in my PATH – Bravo Oct 01 '21 at 00:35

3 Answers3

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This was mostly covered in comments, but this is my take on it.

The reason I have always understood it is that which is showing you which binary is being called; there may be multiple binaries with the same name, but only one will be chosen when you run the command.

which determines which of these binaries is being run by traversing the $PATH environment variable:

[root@headdesk ~]# echo $PATH
/usr/local/sbin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
[root@headdesk ~]#

which is going to look in /usr/local/sbin, then /sbin, and so on.

For example, look at which vim, which is found in the 3rd position of our $PATH:

[root@headdesk ~]# which vim
/bin/vim

If we add an executable with a higher path precedence, we will see the executable we added:

[root@headdesk ~]# >/usr/local/sbin/vim; chmod +x /usr/local/sbin/vim
[root@headdesk ~]# which vim
/usr/local/sbin/vim

If we want to see all vim executables in our path, we can use the -a flag: [root@headdesk ~]# which -a vim /bin/vim /usr/bin/vim

This is covered more concisely in the man page:

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).

cutrightjm
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The etymology is given in an early version of the which program:

which : tells you which program you get

Only Bill Joy could tell you why the question was “which program do I get” rather than “where does the program come from” (but note that asking “where” ends up assuming there’s only one, when the purpose of which was to determine which program would be used out of a potential set of programs).

Stephen Kitt
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Adding to the two excellent answers by cutrightjm and Stephen Kitt, there is a whereis command which does what you say.

From its manpage:

whereis - locate the binary, source, and manual page files for a command
dr_
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