Date: Mon, 27 Apr 2009 02:20:04 GMT From: Garrett Cooper <gcooper@FreeBSD.org> To: freebsd-bugs@FreeBSD.org Subject: Re: bin/124748: [patch] sh(1): sh -c 'exit -1' fails with "Illegal number: -1", instead of exiting with a code of 255 Message-ID: <200904270220.n3R2K4j1049951@freefall.freebsd.org>
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The following reply was made to PR bin/124748; it has been noted by GNATS.
From: Garrett Cooper <gcooper@FreeBSD.org>
To: Garrett Cooper <gcooper@freebsd.org>
Cc: Jilles Tjoelker <jilles@stack.nl>, bug-followup@freebsd.org
Subject: Re: bin/124748: [patch] sh(1): sh -c 'exit -1' fails with "Illegal
number: -1", instead of exiting with a code of 255
Date: Sun, 26 Apr 2009 18:49:38 -0700
On Sun, Apr 26, 2009 at 6:46 PM, Garrett Cooper <gcooper@freebsd.org> wrote=
:
> On Sun, Apr 26, 2009 at 7:40 AM, Jilles Tjoelker <jilles@stack.nl> wrote:
>> Do people actually use 'exit -1' instead of the clearer 'exit 255'? '-1'
>> is not an unsigned integer, so not a posix compliant parameter to the
>> exit special builtin. Even then, sh still aborts a script with a nonzero
>> exit code if exit is used wrongly like this.
>
> Some people do, but I've since then stopped doing this.
>
> The question I have is:
> - Is the value of the return code uint8_t?
> - Where in the documentation for sh(1) does it say that it can't be
> <0? Here are all of the relevant documentation items for exit codes I
> could find:
>
> =A0 Command Exit Status
> =A0 =A0 Each command has an exit status that can influence the behavior o=
f other
> =A0 =A0 shell commands. =A0The paradigm is that a command exits with zero=
for nor-
> =A0 =A0 mal or success, and non-zero for failure, error, or a false indic=
ation.
> =A0 =A0 The man page for each command should indicate the various exit co=
des and
> =A0 =A0 what they mean. =A0Additionally, the built-in commands return exi=
t codes,
> =A0 =A0 as does an executed shell function.
>
> =A0 =A0 If a command is terminated by a signal, its exit status is 128 pl=
us the
> =A0 =A0 signal number. =A0Signal numbers are defined in the header file
> =A0 =A0 <sys/signal.h>.
>
> ----
>
> =A0 =A0 exit [exitstatus]
> =A0 =A0 =A0 =A0 =A0 =A0 Terminate the shell process. =A0If exitstatus is =
given it is used
> =A0 =A0 =A0 =A0 =A0 =A0 as the exit status of the shell; otherwise the ex=
it status of the
> =A0 =A0 =A0 =A0 =A0 =A0 preceding command is used.
>
> ----
>
> Nowhere in the above documentation does it mention valid limits being
> in the set, [0, 128+SIGRTMAX] =3D> [0, 254]. It's merely implied by the
> resources at one's disposal (the source, sys/signal.h, etc).
>
> Thanks,
> -Garrett
Furthermore, exit permits signed integers, which is a different --
much larger -- dataset of valid input values:
EXIT(3) FreeBSD Library Functions Manual EXIT=
(3)
NAME
exit, _Exit -- perform normal program termination
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <stdlib.h>
void
exit(int status);
void
_Exit(int status);
Thanks,
-Garrett
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