Re: [PATCH v2] exec: Print absolute paths for command location queries

On Sat, 13 Jun 2026, at 2:52 AM, Harald van Dijk wrote:
> On 6/13/26 02:47, Herbert Xu wrote:
>> Kerin Millar <[email protected]> wrote:
>>> POSIX requires that, when reporting the location of a utility found by
>>> searching PATH (or one named with a slash), the pathname written by
>>> type, command -v and command -V be absolute:
>>>
>>>     Executable utilities, regular built-in utilities, command_names
>>>     including a <slash> character, and any implementation-provided
>>>     functions that are found using the PATH variable [...] shall be
>>>     written as absolute pathnames.
>>>
>>> Presently, dash fails to conform in this regard. Address this issue by
>>> prefixing relative pathnames with the logical current working directory,
>>> provided that it still resolves to the current directory, and with the
>>> physical current working directory otherwise. If the current working
>>> directory cannot be determined, print the relative pathname instead.
>>>
>>> Link: https://lore.kernel.org/dash/[email protected]/
>>> Reported-by: Christoph Anton Mitterer <[email protected]>
>>> Suggested-by: Harald van Dijk <[email protected]>
>>> Signed-off-by: Kerin Millar <[email protected]>
>>> ---
>>> src/cd.c   | 40 ++++++++++++++++++++++++++++++++++++----
>>> src/cd.h   |  1 +
>>> src/exec.c | 30 ++++++++++++++++++++++++++----
>>> 3 files changed, 63 insertions(+), 8 deletions(-)
>> 
>> Even bash doesn't do this:
>> 
>> $ bash -o posix -c 'cd /; command -v bin/bash'
>> bin/bash
>> $
>
> You're overlooking the "that are found using the PATH variable" from the 
> spec. Because you included a / in the command, it is not looked up from 
> PATH. Modifying your test to make sure PATH is used, we can see that 
> bash does do this in POSIX mode:
>
> $ bash -c 'cd /; PATH=bin command -v bash'
> bin/bash
> $ bash -o posix -c 'cd /; PATH=bin command -v bash'
> /bin/bash

Adjacently, bash willfully supports / in function names.

$ bash -c 'bin/bash() { echo 1; }; bin/bash'
1
$ bash --posix -c 'bin/bash() { echo 1; }; bin/bash'
bash: line 1: bin/bash: No such file or directory

--
Kerin Millar