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Re: empty command redirection

From: Paul Eggert
Subject: Re: empty command redirection
Date: Mon, 11 Oct 2004 14:43:18 -0700
User-agent: Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (gnu/linux)

Alexandre Duret-Lutz <address@hidden> writes:

> With Zsh versions before 3.1.6-dev-18 you had to set `NULLCMD=:'

Thanks for mentioning this.  The NULLCMD stuff is already covered
in the manual (which I had forgotten), but the version info isn't
there so I added this patch:

2004-10-11  Paul Eggert  <address@hidden>

        * doc/autoconf.texi (Shellology, Special Shell Variables):
        Document that the Zsh problem with NULLCMD was fixed in zsh
        3.1.6-dev-18.  Thanks to Alexandre Duret-Lutz for this info.

Index: autoconf.texi
RCS file: /cvsroot/autoconf/autoconf/doc/autoconf.texi,v
retrieving revision 1.836
retrieving revision 1.837
diff -p -u -r1.836 -r1.837
--- autoconf.texi       11 Oct 2004 20:25:41 -0000      1.836
+++ autoconf.texi       11 Oct 2004 21:42:06 -0000      1.837
@@ -9542,7 +9542,8 @@ Substitutions}).
 @cindex Zsh
 To detect whether you are running @command{zsh}, test whether
 @code{ZSH_VERSION} is set.  By default @command{zsh} is @emph{not}
-compatible with the Bourne shell: you have to run @samp{emulate sh} and
+compatible with the Bourne shell: you must execute @samp{emulate sh},
+and for @command{zsh} versions before 3.1.6-dev-18 you must also
 set @code{NULLCMD} to @samp{:}.  @xref{Compatibility,, Compatibility,
 zsh, The Z Shell Manual}, for details.
@@ -10431,9 +10432,10 @@ $ @kbd{sed '=' <lineno |}
 @item NULLCMD
 @evindex NULLCMD
 When executing the command @samp{>foo}, @command{zsh} executes
address@hidden >foo}.  The Bourne shell considers @code{NULLCMD} to be
address@hidden:}, while @command{zsh}, even in Bourne shell compatibility mode,
-sets @code{NULLCMD} to @samp{cat}.  If you forgot to set @code{NULLCMD},
address@hidden >foo} unless it is operating in Bourne shell
+compatibility mode and the @command{zsh} version is newer
+than 3.1.6-dev-18.  If are using an older @command{zsh}
+and forget to set @code{NULLCMD},
 your script might be suspended waiting for data on its standard input.
 @item ENV

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