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From: Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups: comp.unix.shell
Subject: Re: Default PATH setting - reduce to something more sensible?
Date: Sat, 25 Jan 2025 18:07:35 -0800
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Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
> On 24.01.2025 23:00, Keith Thompson wrote:
>> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
>>> On 24.01.2025 14:46, Dan Cross wrote:
>> [...]
>> 
>> /usr/bin/which is limited in what it can do.  It follows POSIX-specified
>> behavior for $PATH; it doesn't recognize any shell-specific rules. [...]
>
> Sure.
>
>> [...]
>>> The settings  PATH=~/bin  and  PATH="~/bin"  respectively shall
>>> result in the same behavior across shells when searching for
>>> programs; in the first case looking into "/home/someuser/bin/"
>>> and in the second case looking into "./~/bin/" (i.e. a path
>>> component with a local directory named "~").
>> 
>> What do you mean by "shall result?
>
> I mean that a shell should behave consistently. (I think Bash does
> not in the given case.)

Consistently with what?  Bash consistently expands literal '~'s in
$PATH, and consistently disables that expansion in POSIX mode.

All shells have shell-specific features.  What's odd about this case is
that bash has a POSIX-violating feature that affects command name
resolution.

If this particular feature were documented, I'd have less of a problem
with it (but I'd still avoid using it).

>> All shells that conform to POSIX behave as you describe.  bash doesn't
>> conform to POSIX unless you ask it to.  Neither do csh, tcsh, and fish.

I should have mentioned that csh, tcsh, and fish don't conform to POSIX
at all.

> We were speaking about shell programming, so [seriously] I don't
> consider Csh and Tcsh as sensible sample shells for the discussion.
> (Thinking about it, I wonder whether Bash inherited tilde-handling
> from Csh, maybe; that would at least explain something.)

No, csh and tcsh (at least in current versions) don't expand literal
'~'s in $PATH.

> (I don't know Fish, so I cannot comment on that.)

Nor do I.

I don't mind excluding non-Bournish shells like csh, tcsh, and
fish from the discussion, but I like to mention now and then that
they're being excluded.  They are shells, after all.

>> [...]
>
>> BTW, it hadn't occurred to me that you can have a relative path in a
>> component of $PATH, but it does seem to work.  I won't be taking
>> advantage of this information.
>
> Yes. Some prefer to add '.' to PATH. (Though I have no intention
> to discuss that habit.)

Right, of course '.' is a relative path.  I should have thought of that.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */