From: Akim Demaille <akim@epita.fr>
Date: Thu, 2 Nov 2000 17:35:53 +0000 (+0000)
Subject: * doc/autoconf.texi (Limitations of Usual Tools): Some about
X-Git-Tag: autoconf-2.50~479
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5243fda44e034ad8324ec32fa8e08faf8e372f25;p=thirdparty%2Fautoconf.git

* doc/autoconf.texi (Limitations of Usual Tools): Some about
dirname.
---

diff --git a/ChangeLog b/ChangeLog
index 83195cf2e..cc4298b98 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2000-11-02  Akim Demaille  <akim@epita.fr>
+
+	* doc/autoconf.texi (Limitations of Usual Tools): Some about
+	dirname.
+
 2000-11-02  Pavel Roskin  <proski@gnu.org>
 
 	* ifnames.sh: Put the opening brace on the same line with
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 7b87faec7..491d5c16f 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -5528,10 +5528,46 @@ $ gawk 'function die () @{ print "Aaaaarg!"  @}
 Aaaaarg!
 @end example
 
+
 @item @command{cat}
 @cindex @command{cat}
 Don't rely on any option.
 
+
+@item @command{dirname}
+@cindex @command{dirname}
+Not all hosts have @command{dirname}, but it is reasonably easy to
+emulate, e.g.:
+
+@example
+dir=`expr "x$file" : 'x\(.*\)/[^/]*' \|
+          '.'      : '.'
+@end example
+
+@noindent
+But there are a few subtilities, e.g., under UN*X, should @samp{//1}
+give @samp{/}?  Paul Eggert answers:
+
+@quotation
+No, under some older flavors of Unix, leading @samp{//} is a special
+path name: it refers to a "super-root" and is used to access other
+machines' files.  Leading @samp{///}, @samp{////}, etc. are equivalent
+to @samp{/}; but leading @samp{//} is special.  I think this tradition
+started with Apollo Domain/OS, an OS that is still in use on some older
+hosts.
+
+POSIX.2 allows but does not require the special treatment for @samp{//}.
+It says that the behavior of dirname on path names of the form
+@samp{//([^/]+/*)?}  is implementation defined.  In these cases, GNU
+@command{dirname} returns @samp{/}, but it's more portable to return
+@samp{//} as this works even on those older flavors of Unix.
+
+I have heard rumors that this special treatment of @samp{//} may be
+dropped in future versions of POSIX, but for now it's still the
+standard.
+@end quotation
+
+
 @item @command{egrep}
 @cindex @command{egrep}
 The empty alternative is not portable, use @samp{?} instead. For
diff --git a/lib/m4sugar/m4sh.m4 b/lib/m4sugar/m4sh.m4
index e2b47a776..70cb29595 100644
--- a/lib/m4sugar/m4sh.m4
+++ b/lib/m4sugar/m4sh.m4
@@ -132,24 +132,6 @@ done; }
 # Simulate running `dirname(1)' on PATHNAME, not all systems have it.
 # This macro must be usable from inside ` `.
 #
-# Paul Eggert answers:
-# Question: Under UN*X, should `//1' give `/'?
-#
-#   No, under some older flavors of Unix, leading // is a special path
-#   name: it refers to a "super-root" and is used to access other
-#   machines' files.  Leading ///, ////, etc. are equivalent to /; but
-#   leading // is special.  I think this tradition started with Apollo
-#   Domain/OS, an OS that is still in use on some older hosts.
-#
-#   POSIX.2 allows but does not require the special treatment for //.
-#   It says that the behavior of dirname on path names of the form
-#   //([^/]+/*)? is implementation defined.  In these cases, GNU dirname
-#   returns /, but it's more portable to return // as this works even on
-#   those older flavors of Unix.
-#
-#   I have heard rumors that this special treatment of // may be dropped
-#   in future versions of POSIX, but for now it's still the standard.
-#
 # Prefer expr to echo|sed, since expr is usually faster and it handles
 # backslashes and newlines correctly.  However, older expr
 # implementations (e.g. SunOS 4 expr and Solaris 8 /usr/ucb/expr) have
diff --git a/m4sh.m4 b/m4sh.m4
index e2b47a776..70cb29595 100644
--- a/m4sh.m4
+++ b/m4sh.m4
@@ -132,24 +132,6 @@ done; }
 # Simulate running `dirname(1)' on PATHNAME, not all systems have it.
 # This macro must be usable from inside ` `.
 #
-# Paul Eggert answers:
-# Question: Under UN*X, should `//1' give `/'?
-#
-#   No, under some older flavors of Unix, leading // is a special path
-#   name: it refers to a "super-root" and is used to access other
-#   machines' files.  Leading ///, ////, etc. are equivalent to /; but
-#   leading // is special.  I think this tradition started with Apollo
-#   Domain/OS, an OS that is still in use on some older hosts.
-#
-#   POSIX.2 allows but does not require the special treatment for //.
-#   It says that the behavior of dirname on path names of the form
-#   //([^/]+/*)? is implementation defined.  In these cases, GNU dirname
-#   returns /, but it's more portable to return // as this works even on
-#   those older flavors of Unix.
-#
-#   I have heard rumors that this special treatment of // may be dropped
-#   in future versions of POSIX, but for now it's still the standard.
-#
 # Prefer expr to echo|sed, since expr is usually faster and it handles
 # backslashes and newlines correctly.  However, older expr
 # implementations (e.g. SunOS 4 expr and Solaris 8 /usr/ucb/expr) have