Re: [PATCH] Allow shell scripts to run with non-Bash /bin/sh

2 messages, 2 authors, 2016-06-15 · open the first message on its own page

Re: [PATCH] Allow shell scripts to run with non-Bash /bin/sh

From: Junio C Hamano <hidden>
Date: 2016-06-15 22:43:36

Eygene Ryabinkin [off-list ref] writes:
OK, you're right.  Especially if /bin/sh from Solaris and OpenBSD
are working and they are not Bash.  But I would not tell that
the shell is broken now -- I had not seen the POSIX specification.
Does it specifies how the shell should work in this case?
I have always been assuming it to be the case (this construct is
not my invention but is an old school idiom I just inherited
from my mentor) and never looked at the spec recently, but I
re-read it just to make sure.  The answer is yes.

Visit http://www.opengroup.org/onlinepubs/000095399/ and follow
"Shell and Utilities volume (XCU)" and then "Case conditional
construct".

    Exit Status

    The exit status of case shall be zero if no patterns are
    matched. Otherwise, the exit status shall be the exit status of
    the last command executed in the compound-list.

So, as David suggests, if

        false
        case Ultra in
        Super) false ;;
        Hyper) true ;;
        esac && echo case returned ok

does not say "case returned ok", then the shell has a bit of
problem.

Re: [PATCH] Allow shell scripts to run with non-Bash /bin/sh

From: Eygene Ryabinkin <hidden>
Date: 2016-06-15 22:43:36

Junio, *, good day.

Sat, Sep 22, 2007 at 01:32:38AM -0700, Junio C Hamano wrote:
quoted
OK, you're right.  Especially if /bin/sh from Solaris and OpenBSD
are working and they are not Bash.  But I would not tell that
the shell is broken now -- I had not seen the POSIX specification.
Does it specifies how the shell should work in this case?
I have always been assuming it to be the case (this construct is
not my invention but is an old school idiom I just inherited
from my mentor) and never looked at the spec recently, but I
re-read it just to make sure.  The answer is yes.

Visit http://www.opengroup.org/onlinepubs/000095399/ and follow
"Shell and Utilities volume (XCU)" and then "Case conditional
construct".
Yes, thanks for the pointer.
So, as David suggests, if

        false
        case Ultra in
        Super) false ;;
        Hyper) true ;;
        esac && echo case returned ok

does not say "case returned ok", then the shell has a bit of
problem.
Correct: the current /bin/sh for FreeBSD does not set zero exit
code if no case patterns were matched.  So, I apologize for my quick
decision on the non-brokenness of the /bin/sh -- it is broken.

I had fixed the shell and filed the problem report.  May be the
change will be incorporated into the future release of FreeBSD.
Meanwhile, I had added workarounds to the other places Junio mentioned
in his follow-up and will try to push this patch to the FreeBSD
port of Git.  The explanation had been changed too ;))

Thanks to all people who helped me to realize what is wrong and where!
-- 
Eygene
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