FYI: Some doc about /usr/xpg4/bin/sh

[Akim Demaille]

>From some old message from Russ and Robert.  Please, Russ and Robert,
if you don't like me citing your names, tell me, I'll clean this out.

Index: ChangeLog
from  Akim Demaille  <address@hidden>
        * doc/autoconf.texi (Shellology): Some about /usr/xpg4/bin/sh on
        Solaris.
        Sort the entries.
        Some words about POSIX vs Bourne shell.
        From Russ Allbery and Robert Lipe.

Index: THANKS
===================================================================
RCS file: /cvs/autoconf/THANKS,v
retrieving revision 1.43
diff -u -u -t -r1.43 THANKS
--- THANKS 2000/11/03 11:59:39 1.43
+++ THANKS 2000/11/10 12:06:42
@@ -4,7 +4,7 @@
 
 Aaron Crane             address@hidden
 Aharon Robbins          address@hidden
-Akim Demaille           address@hidden
+Akim Demaille           address@hidden
 Alain Knaff             address@hidden
 Alec Wolman             address@hidden
 Alexandre Oliva         address@hidden
@@ -110,6 +110,7 @@
 Ralf Corsepius          address@hidden
 Ralf S. Engelschall     address@hidden
 Richard Stallman        address@hidden
+Robert Lipe             address@hidden
 Robert S. Maier         address@hidden
 Roland McGrath          address@hidden
 Ruediger Kuhlmann       address@hidden
Index: doc/autoconf.texi
===================================================================
RCS file: /cvs/autoconf/doc/autoconf.texi,v
retrieving revision 1.376
diff -u -u -t -r1.376 autoconf.texi
--- doc/autoconf.texi 2000/11/10 11:45:45 1.376
+++ doc/autoconf.texi 2000/11/10 12:07:05
@@ -5002,22 +5002,6 @@
 Below we describe some of the members of the Bourne shell family.
 
 @table @asis
address@hidden @command{bash}
address@hidden @command{bash}
-To detect whether you are running @command{bash}, test if
address@hidden is set.  To disable its extensions and require
address@hidden compatibility, run @samp{set -o posix}. @xref{Bash POSIX
-Mode,, Bash @sc{posix} Mode, bash, The GNU Bash Reference Manual}, for
-details.
-
address@hidden @command{zsh}
address@hidden @command{zsh}
-To detect whether you are running @command{zsh}, test if
address@hidden is set.  By default @command{zsh} is @emph{not}
-compatible with the Bourne shell: you have to run @samp{emulate sh} and
-set @code{NULLCMD} to @samp{:}. @xref{Compatibility,, Compatibility,
-zsh, The Z Shell Manual}, for details.
-
 @item @command{ash}
 @cindex @command{ash}
 @command{ash} is often used on @sc{gnu}/Linux and @sc{bsd} systems as a
@@ -5065,8 +5049,58 @@
 `exit 1` || echo "ash won't print it"
 @end example
 
address@hidden @command{bash}
address@hidden @command{bash}
+To detect whether you are running @command{bash}, test if
address@hidden is set.  To disable its extensions and require
address@hidden compatibility, run @samp{set -o posix}. @xref{Bash POSIX
+Mode,, Bash @sc{posix} Mode, bash, The GNU Bash Reference Manual}, for
+details.
+
address@hidden @command{/usr/xpg4/bin/sh} on Solaris
address@hidden @command{/usr/xpg4/bin/sh} on Solaris
+The @sc{posix}-compliant Bourne shell on a Solaris system is
address@hidden/usr/xpg4/bin/sh} and is part of an extra optional package.
+There is no extra charge for this package, but it is also not part of a
+minimal OS install and therefore some folks may not have it.
+
address@hidden @command{zsh}
address@hidden @command{zsh}
+To detect whether you are running @command{zsh}, test if
address@hidden is set.  By default @command{zsh} is @emph{not}
+compatible with the Bourne shell: you have to run @samp{emulate sh} and
+set @code{NULLCMD} to @samp{:}. @xref{Compatibility,, Compatibility,
+zsh, The Z Shell Manual}, for details.
 @end itemize
 @end table
+
+The following discussion between Russ Allbery and Robert Lipe is worth
+reading:
+
address@hidden
+Russ Allbery:
+
address@hidden
+The @sc{gnu} assumption that @command{/bin/sh} is the one and only shell
+leads to a permanent deadlock.  Vendors don't want to break user's
+existant shell scripts, and there are some corner cases in the Bourne
+shell that are not completely compatible with a @sc{posix} shell.  Thus,
+vendors who have taken this route will @emph{never} (OK... ``never say
+never'') replace the Bourne shell (as @command{/bin/sh}) with a
address@hidden shell.
address@hidden quotation
+
address@hidden
+Robert Lipe:
+
address@hidden
+This is exactly the problem.  While most (at least most System V's) do
+have a bourne shell that accepts shell functions most vendor
address@hidden/bin/sh} programs are not the @sc{posix} shell.
+
+So while most modern systems do have a shell _somewhere_ that meets the
address@hidden standard, the challenge is to find it.
address@hidden quotation
 
 
 @node Shell Substitutions, Assignments, Shellology, Portable Shell