Document sed limitation with escaped metacharacters.

* doc/autoconf.texi (Limitations of Usual Tools) <sed>: Use `%'
rather than `/' as delimiter in an example `s' command.
Document inconsistent treatment of escaped metacharacters.
* THANKS: Update.
Report by Dave Korn, with additional input from Paolo Bonzini
and Eric Blake.

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>

diff --git a/ChangeLog b/ChangeLog
index 9079a0ea9c32a2b3657586de4b4085200dbd200d..80f560994715170d56142239ca589e4df19ee7b8 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2009-09-10  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
 
+       Document sed limitation with escaped metacharacters.
+       * doc/autoconf.texi (Limitations of Usual Tools) <sed>: Use `%'
+       rather than `/' as delimiter in an example `s' command.
+       Document inconsistent treatment of escaped metacharacters.
+       * THANKS: Update.
+       Report by Dave Korn, with additional input from Paolo Bonzini
+       and Eric Blake.
+
        Document temporary directory `$tmp' for use in config.status.
        * doc/autoconf.texi (Configuration Actions): Document `$tmp'.
        * NEWS: Update.

diff --git a/THANKS b/THANKS
index 460e68052a7ecb132f5c2b886e0002ba31fd0e25..0901d6ac74371ac84e008bb9c9ae6e63426404c5 100644 (file)
--- a/THANKS
+++ b/THANKS
@@ -86,6 +86,7 @@ Daniel Reed                 ?
 Daniele Arena               daniele@ripe.net
 Dave Adams                  adams@hpesdwa.fc.hp.com
 Dave Erickson               retrorandomaccess@hotmail.com
+Dave Korn                   dave.korn.cygwin@googlemail.com
 Dave Love                   fx@gnu.org
 David Byron                 dbyron@hheld.com
 David Carter                david@carter.net

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 320ef238eee35f374f4ab29e518af46b56054845..82a9f2aa3d1963e2b12ea5bf2c8bd25b75f1b88e 100644 (file)
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -17511,7 +17511,11 @@ directory.
 @prindex @command{sed}
 Patterns should not include the separator (unless escaped), even as part
 of a character class.  In conformance with Posix, the Cray
-@command{sed} rejects @samp{s/[^/]*$//}: use @samp{s,[^/]*$,,}.
+@command{sed} rejects @samp{s/[^/]*$//}: use @samp{s%[^/]*$%%}.
+Even when escaped, patterns should not include separators that are also
+used as @command{sed} metacharacters.  For example, GNU sed 4.0.9 rejects
+@samp{s,x\@{1\,\@},,}, while sed 4.1 strips the backslash before the comma
+before evaluating the basic regular expression.
 
 Avoid empty patterns within parentheses (i.e., @samp{\(\)}).  Posix does
 not require support for empty patterns, and Unicos 9 @command{sed} rejects