Re: sed --posix does not catch incomplete arguments

[Bruno Haible]

Hi,

Eric Blake reported in
<http://lists.gnu.org/archive/html/bug-gnu-utils/2010-06/msg00060.html>:
> The Austin group
> take this morning is that allowing -e fragments is a useful addition for
> the next revision of the standard, but that there are still
> implementations today (like AIX) that don't support it now, so it will
> be several years before sed -e 1{ -e } is standardized.

So, meanwhile, let's document the portability problem in the Autoconf
manual.

Here's what I see on Solaris 10:

  $ echo a | sed -n -e 'i\' -e 0
  Unrecognized command: 0

And on HP-UX 11:

  $ echo a | sed -n -e 'i\' -e 0
  sed: Found escape character at end of editing script.

And on AIX 4:

  $ echo a | sed -n -e 'i\' -e 0
  sed: 0602-403 0 is not a recognized function.

Here's a proposed patch.


2010-06-18  Bruno Haible  <address@hidden>

        * doc/autoconf.texi (Limitations of Usual Tools): Mention portability
        problem of sed -e option with script fragments.

*** doc/autoconf.texi.orig      Fri Jun 18 14:40:10 2010
--- doc/autoconf.texi   Fri Jun 18 14:38:20 2010
***************
*** 18237,18242 ****
--- 18237,18258 ----
  should use semicolon only with simple scripts that do not use these
  verbs.
  
+ The argument of the @option{-e} option must be a syntactically complete
+ script.  GNU @command{sed} allows to pass multiple script fragments,
+ each as argument of a separate @option{-e} option, that are then combined,
+ with newlines between the fragments.  A future Posix revision may allow
+ this as well.  But in Posix:2008, this is not allowed, and the
+ @command{sed} programs on Solaris 10, HP-UX 11, and AIX don't allow it
+ either:
+ 
+ @example
+ $ @kbd{echo a | sed -n -e 'i\}
+ @kbd{0'}
+ 0
+ $ @kbd{echo a | sed -n -e 'i\' -e 0}
+ Unrecognized command: 0
+ @end example
+ 
  Commands inside @{ @} brackets are further restricted.  Posix says that
  they cannot be preceded by addresses, @samp{!}, or @samp{;}, and that
  each command must be followed immediately by a newline, without any