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* doc/autoconf.texi (Limitations of Builtins, Limitations of Make):

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Mention more problems with the -e option.
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Paul Eggert 2006-05-01 17:35:50 +00:00
parent 100f26c15e
commit b5ade1c2b2
2 changed files with 48 additions and 4 deletions
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@ -1,3 +1,9 @@
2006-05-01 Paul Eggert <eggert@cs.ucla.edu>
and Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
* doc/autoconf.texi (Limitations of Builtins, Limitations of Make):
Mention more problems with the -e option.
2006-04-30 Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
* NEWS: Typo.

46
doc/autoconf.texi
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@ -12143,10 +12143,14 @@ Also please see the discussion of the @command{cd} command.
@item @command{set}
@c ----------------
@prindex @command{set}
This builtin faces the usual problem with arguments starting with a
With the Free@acronym{BSD} 6.0 shell, the @command{set} command (without
any options) does not sort its output.
The @command{set} builtin faces the usual problem with arguments starting with a
dash. Modern shells such as Bash or Zsh understand @option{--} to specify
the end of the options (any argument after @option{--} is a parameter,
even @samp{-x} for instance), but most shells simply stop the option
even @samp{-x} for instance), but many traditional shells (e.g., Solaris
10 @command{/bin/sh}) simply stop option
processing as soon as a non-option argument is found. Therefore, use
@samp{dummy} or simply @samp{x} to end the option processing, and use
@command{shift} to pop it out:
@ -12168,8 +12172,37 @@ better to combine them:
set -ex
@end example
The @command{set} of the Free@acronym{BSD} 6.0 shell does not sort its
output.
The @acronym{BSD} shell has had several problems with the @option{-e}
option, partly because @acronym{BSD} @command{make} traditionally used
@option{-e} even though this was incompatible with Posix
(@pxref{Limitations of Make}). Older versions of the @acronym{BSD}
shell (circa 1990) mishandled @samp{&&}, @samp{||}, @samp{if}, and
@samp{case} when @option{-e} was in effect, causing the shell to exit
unexpectedly in some cases. This was particularly a problem with
makefiles, and led to circumlocutions like @samp{sh -c 'test -f file ||
touch file'}, where the seemingly-unnecessary @samp{sh -c '@dots{}'}
wrapper works around the bug.
Even relatively-recent versions of the @acronym{BSD} shell (e.g.,
Open@acronym{BSD} 3.4) wrongly exit with @option{-e} if a command within
@samp{&&} fails inside a compound statement. For example:
@example
#! /bin/sh
set -e
foo='nonempty'
test -n "$foo" && exit 1
echo one
if :; then
test -n "$foo" && exit 1
fi
echo two
@end example
@noindent
does not print @samp{two}. One workaround is to use @samp{if test -n
"$foo"; then exit 1; fi} rather than @samp{test -n "$foo" && exit 1}.
Another possibility is to warn @acronym{BSD} users not to use @samp{sh -e}.
@item @command{shift}
@ -13351,6 +13384,11 @@ remove @file{U} with Posix make, but incompatible
@command{touch} fails. One way to work around this is to reword the
affected simple-commands so that they always succeed, e.g., @samp{touch
T || :; rm -f U}.
However, even this approach can run into common bugs in BSD
implementations of the @option{-e} option of @command{sh} and
@command{set} (@pxref{Limitations of Builtins}), so if you are worried
about porting to buggy BSD shells it may be simpler to migrate
complicated @command{make} actions into separate scripts.
@item Leading underscore in macro names
Some @command{make}s don't support leading underscores in macro names,