Re: When "set -u", "which" outputs environment: line 1: _declare: unbound

[Eli Schwartz]

On 4/9/21 4:22 PM, Greg Wooledge wrote:
> On Fri, Apr 09, 2021 at 03:08:25PM -0400, Craig Andrews wrote:
>> Description:
>>         With "set -u", invoking "which" results in the output of:
>> environment: line 1: _declare: unboundvariable
>>         That should not happen, and does not happen, with prior versions of
>> bash.
>>         I'm using Fedora 34 (beta).
>>
>> Repeat-By:
>>         Run this shell script:
>>         #!/bin/bash
>>         set -u
>>         echo "$(which bash)"
>>
> 
> I can think of two possible reasons for this:
> 
> 1) which(1) on your system is a bash script, and the error message is
>    coming from that script.
> 
> 2) which on your system is a shell function, which is somehow made visible
>    to the script that you ran (possibly having been exported through the
>    environment, or declared in a file that's loaded via BASH_ENV).
> 
> Are you able to duplicate the error by running "which bash" in an
> interactive shell, or does it only happen in scripts?
> 
> In whatever environment generates the error message, please run "type which"
> to find out exactly how which is defined.
> 
> If it's a program (e.g. /usr/bin/which), please run "file" on that program
> to see whether it's a (bash) script.
> 
> If it's a function, try to figure out where the function is being defined.


Are you ready to have your day truly spoiled? Fedora's package for the
external program GNU which, provides this /etc/profile.d/ script
(automatically injected into the environment of any interactive shell
sessions once you install GNU which -- how charming):

https://src.fedoraproject.org/rpms/which/blob/rawhide/f/which2.sh

Corresponding to the terrible advice from the GNU which manpage:

https://man.archlinux.org/man/which.1#EXAMPLE

So, it will on every `which` invocation feed the result of `alias;
declare -f` to ` | which --weird-options` and, essentially, reinvent
`type -a`.

-- 
Eli Schwartz
Arch Linux Bug Wrangler and Trusted User

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