[pacman-dev] sourcing /etc/profile and set -e bug in makepkg

[Xavier]

On Mon, Aug 11, 2008 at 5:24 PM, Allan McRae <allan at archlinux.org> wrote:
> So, despite me assuring Dan that nothing could possibly go wrong, the commit
> to source /etc/profile rather than individual files in /etc/profile.d
> (http://projects.archlinux.org/?p=pacman.git;a=commitdiff;h=0e0a8461) has
> caused a problem.  See FS#11179 (http://bugs.archlinux.org/task/11179) for
> more details.
>
> Xavier and I are stuck as to what is actually causing this problem.  The
> guilty script being sourced is /etc/bash_completion.d/modules and
> specifically the "type modules" statement at the top.  What we don't
> understand is that this file is being sourced under both methods and why it
> is causing problems only with one.  Even more confusing, the way it gets
> sourced in /etc/profile is essentially the way makepkg used to do it (loop
> over /etc/profile.d/* files).
>
> A work-around is to add "set +e" and "set -e" on either side of the "source
> /etc/profile" call.  That is probably a good idea anyway as that sourcing
> should probably not inherit the "-e" property.  But can anyone explain why
> we now need this?
>
> Very confused,
> Allan
>

Ahah, I was also confused, and desperate of figuring it out, but I
finally did :)
The reason is the /etc/profile.d/bash_completion.sh script
It checks for the existence of $PS1, apparently for guessing if the
shell is interactive or not.
Isn't this a broken assumption?

Because when the new makepkg 3.2.0 sources /etc/profile, then PS1 is
defined there. Though it was not an interactive shell.
On the other hand, when we have another script, like the old makepkg (
<= 3.1), which sources /etc/profile.d/bash_completion.sh directly,
then PS1 is not defined, and /etc/bash_completion is not sourced. So
we could not detect the breakage caused by
/etc/bash_completion.d/modules before.

Here are the information I found about how to detect an interactive shell :
http://www.faqs.org/faqs/unix-faq/faq/part5/section-5.html
This indeed mention checking $PS1 but also says checking $- is better.
And that would work indeed.

But this info is very old, and the following one looks much more recent :
http://defindit.com/readme_files/bash_examples.html
"Using shopt -q login_shell seems to be the modern and reliable way to
detect interactive shell sessions."

So if we fix the detection of interactive shell in
/etc/profile.d/bash_completion.sh , then we don't have to edit
anything in makepkg.
It will still source /etc/profile.d/bash_completion.sh but will stop
here and not source /etc/bash_completion