Find the path of a shell command

[Jon Ribbens]

On 2022-10-12, Michael F. Stemper <michael.stemper at gmail.com> wrote:
> On 12/10/2022 07.20, Chris Green wrote:
>> ... and rm will just about always be in /usr/bin.
>
> On two different versions of Ubuntu, it's in /bin.

It will almost always be in /bin in any Unix or Unix-like system,
because it's one of the fundamental utilities that may be vital in
fixing the system when it's booted in single-user mode and /usr may
not be available. Also, the Filesystem Hierarchy Standard *requires*
it to be in /bin.

Having said that, nothing requires it not to be elsewhere *as well*,
and in Ubuntu and other Linux systems it is in /usr/bin too. And because
PATH for non-root users will usually contain /usr/bin before /bin (or
indeed may not contain /bin at all), 'command -v rm' or 'which rm' will
usually list the version of rm that is in /usr/bin.

e.g. on Amazon Linux:

    $ which rm
    /usr/bin/rm
    $ sudo which rm
    /bin/rm