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Date:      Mon, 24 May 2021 03:12:24 +0000
From:      bugzilla-noreply@freebsd.org
To:        ports-bugs@FreeBSD.org
Subject:   [Bug 208391] misc/mc SUBSHELL not working with /bin/sh
Message-ID:  <bug-208391-7788-GuSyXjScqu@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-208391-7788@https.bugs.freebsd.org/bugzilla/>
References:  <bug-208391-7788@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D208391

Alexey Dokuchaev <danfe@FreeBSD.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|ports-bugs@FreeBSD.org      |danfe@FreeBSD.org
           Severity|Affects Only Me             |Affects Some People
             Status|Open                        |In Progress
                 CC|                            |danfe@FreeBSD.org

--- Comment #6 from Alexey Dokuchaev <danfe@FreeBSD.org> ---
(In reply to Patrick McMunn from comment #2)
> This is a longstanding bug.
Well, it depends on one's definition of a bug. :-)  Technically, ``env
SHELL=3D/bin/sh mc'' tells users up-front that this combination is unsuppor=
ted
and refuses to work.  It could probably emit less cryptic diagnostics, but
that's about it.  It's simply not possible to support /bin/sh as a subshell=
 in
a way mc(1) deals with shells.

When it launches a subshell, mc(1) installs so called "precmd" hook (execut=
ed
before each prompt) so the shell can report its current working directory b=
ack
to mc(1).  Some shells are advanced enough and provide this feature out of =
the
box, e.g. for bash(1):

> echo $PROMPT_COMMAND
> pwd>&7;kill -STOP $$
For tcsh(1):

> alias
> ...
> precmd  echo $cwd:q >>/tmp/mc-danfe/mc.pipe.78491; kill -STOP $$
Other supported shells like dash(1) are not so advanced, but they support
command expansion in the PS1, so this behavior can be emulated.  Alas, our
/bin/sh supports none of these.

> I would suggest that the subshell build option be disabled by default
We should not cripple package defaults just for the sake of ~1% of users who
are confined to /bin/sh as their interactive shell.

> or that, at the very least, an informational message be emitted that a us=
er
> either needs to use the -u option to start or that the user's default she=
ll
> should be changed
Yes, that's what we should do.  I'll take Mateusz's text but rework it, as =
it's
a bit too wordy while lacking technical details about this issue.

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