bin/124748: [patch] sh(1): sh -c 'exit -1' fails with "Illegal number: -1", instead of exiting with a code of 255

Garrett Cooper gcooper at
Mon Apr 27 02:20:05 UTC 2009

The following reply was made to PR bin/124748; it has been noted by GNATS.

From: Garrett Cooper <gcooper at>
To: Garrett Cooper <gcooper at>
Cc: Jilles Tjoelker <jilles at>, bug-followup at
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 at> wrote=
 > On Sun, Apr 26, 2009 at 7:40 AM, Jilles Tjoelker <jilles at> 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=
 > =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=
      exit, _Exit -- perform normal program termination
      Standard C Library (libc, -lc)
      #include <stdlib.h>
      exit(int status);
      _Exit(int status);

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