diff --git a/ChangeLog b/ChangeLog
index b0498601..7c47166b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2000-11-16  Akim Demaille  <akim@epita.fr>
+
+	POSIX doesn't require s/[^/]// to work.
+	From Paul Eggert and Johan Danielsson.
+
+	* doc/autoconf.texi (Limitations of Usual Tools) <sed>:
+	Reorganize.  Document this issue.
+	* autoupdate.sh (dir): Use `,' as separator instead of `/'
+	* autoreconf.sh: Likewise.
+	* autoupdate.sh: Ditto.
+
 2000-11-16  Paul Eggert  <eggert@twinsun.com>
 
 	* m4/largefile.m4 (_AC_SYS_LARGEFILE_SOURCE): Remove, replaced by...
diff --git a/autoheader.in b/autoheader.in
index 9dac38fd..274a2c1f 100644
--- a/autoheader.in
+++ b/autoheader.in
@@ -81,7 +81,7 @@ if test "${LC_CTYPE+set}"    = set; then LC_CTYPE=C;    export LC_CTYPE;    fi
 
 # Variables.
 : ${autoconf_dir=${AC_MACRODIR=@datadir@}}
-dir=`echo "$0" | sed -e 's/[^/]*$//'`
+dir=`echo "$0" | sed -e 's,[^/]*$,,'`
 # We test "$dir/autoconf" in case we are in the build tree, in which case
 # the names are not transformed yet.
 for autoconf in "$AUTOCONF" \
@@ -293,7 +293,7 @@ test -r $config_h.top && cat $config_h.top >>$tmp/config.hin
 
 # Dump `acconfig.h' but its bottom.
 test -r $localdir/acconfig.h &&
-  sed -e '/@BOTTOM@/,$d' -e 's/@TOP@//' $localdir/acconfig.h >>$tmp/config.hin
+  sed '/@BOTTOM@/,$d;s/@TOP@//' $localdir/acconfig.h >>$tmp/config.hin
 
 # Dump the templates from `configure.in'.
 for verb in `(set) 2>&1 | sed -n -e '/^ac_verbatim/s/^\([^=]*\)=.*$/\1/p' | sort`; do
diff --git a/autoheader.sh b/autoheader.sh
index 9dac38fd..274a2c1f 100644
--- a/autoheader.sh
+++ b/autoheader.sh
@@ -81,7 +81,7 @@ if test "${LC_CTYPE+set}"    = set; then LC_CTYPE=C;    export LC_CTYPE;    fi
 
 # Variables.
 : ${autoconf_dir=${AC_MACRODIR=@datadir@}}
-dir=`echo "$0" | sed -e 's/[^/]*$//'`
+dir=`echo "$0" | sed -e 's,[^/]*$,,'`
 # We test "$dir/autoconf" in case we are in the build tree, in which case
 # the names are not transformed yet.
 for autoconf in "$AUTOCONF" \
@@ -293,7 +293,7 @@ test -r $config_h.top && cat $config_h.top >>$tmp/config.hin
 
 # Dump `acconfig.h' but its bottom.
 test -r $localdir/acconfig.h &&
-  sed -e '/@BOTTOM@/,$d' -e 's/@TOP@//' $localdir/acconfig.h >>$tmp/config.hin
+  sed '/@BOTTOM@/,$d;s/@TOP@//' $localdir/acconfig.h >>$tmp/config.hin
 
 # Dump the templates from `configure.in'.
 for verb in `(set) 2>&1 | sed -n -e '/^ac_verbatim/s/^\([^=]*\)=.*$/\1/p' | sort`; do
diff --git a/autoreconf.in b/autoreconf.in
index 44977b01..907e1da0 100644
--- a/autoreconf.in
+++ b/autoreconf.in
@@ -91,7 +91,7 @@ if test "${LC_CTYPE+set}"    = set; then LC_CTYPE=C;    export LC_CTYPE;    fi
 # Variables.
 : ${autoconf_dir=${AC_MACRODIR=@datadir@}}
 debug=false
-dir=`echo "$0" | sed -e 's/[^/]*$//'`
+dir=`echo "$0" | sed -e 's,[^/]*$,,'`
 force=false
 # --install -- as --add-missing in other tools.
 install=false
diff --git a/autoreconf.sh b/autoreconf.sh
index 44977b01..907e1da0 100644
--- a/autoreconf.sh
+++ b/autoreconf.sh
@@ -91,7 +91,7 @@ if test "${LC_CTYPE+set}"    = set; then LC_CTYPE=C;    export LC_CTYPE;    fi
 # Variables.
 : ${autoconf_dir=${AC_MACRODIR=@datadir@}}
 debug=false
-dir=`echo "$0" | sed -e 's/[^/]*$//'`
+dir=`echo "$0" | sed -e 's,[^/]*$,,'`
 force=false
 # --install -- as --add-missing in other tools.
 install=false
diff --git a/bin/autoheader.in b/bin/autoheader.in
index 9dac38fd..274a2c1f 100644
--- a/bin/autoheader.in
+++ b/bin/autoheader.in
@@ -81,7 +81,7 @@ if test "${LC_CTYPE+set}"    = set; then LC_CTYPE=C;    export LC_CTYPE;    fi
 
 # Variables.
 : ${autoconf_dir=${AC_MACRODIR=@datadir@}}
-dir=`echo "$0" | sed -e 's/[^/]*$//'`
+dir=`echo "$0" | sed -e 's,[^/]*$,,'`
 # We test "$dir/autoconf" in case we are in the build tree, in which case
 # the names are not transformed yet.
 for autoconf in "$AUTOCONF" \
@@ -293,7 +293,7 @@ test -r $config_h.top && cat $config_h.top >>$tmp/config.hin
 
 # Dump `acconfig.h' but its bottom.
 test -r $localdir/acconfig.h &&
-  sed -e '/@BOTTOM@/,$d' -e 's/@TOP@//' $localdir/acconfig.h >>$tmp/config.hin
+  sed '/@BOTTOM@/,$d;s/@TOP@//' $localdir/acconfig.h >>$tmp/config.hin
 
 # Dump the templates from `configure.in'.
 for verb in `(set) 2>&1 | sed -n -e '/^ac_verbatim/s/^\([^=]*\)=.*$/\1/p' | sort`; do
diff --git a/bin/autoreconf.in b/bin/autoreconf.in
index 44977b01..907e1da0 100644
--- a/bin/autoreconf.in
+++ b/bin/autoreconf.in
@@ -91,7 +91,7 @@ if test "${LC_CTYPE+set}"    = set; then LC_CTYPE=C;    export LC_CTYPE;    fi
 # Variables.
 : ${autoconf_dir=${AC_MACRODIR=@datadir@}}
 debug=false
-dir=`echo "$0" | sed -e 's/[^/]*$//'`
+dir=`echo "$0" | sed -e 's,[^/]*$,,'`
 force=false
 # --install -- as --add-missing in other tools.
 install=false
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index ba161cbc..5d123730 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -5885,8 +5885,26 @@ don't rely on symbolic links on @sc{djgpp}.
 
 @item @command{sed}
 @cindex @command{sed}
+Patterns should not include the separator (unless escaped), even as part
+of a character class.  In conformance with @sc{posix}, the Cray
+@command{sed} will reject @samp{s/[^/]*$//}: use @samp{s,[^/]*$,,}.
+
+Sed scripts should not use branch labels longer than 8 characters and
+should not contain comments.
+
+Input should have reasonably long lines, since some @command{sed} have
+an input buffer limited to 4000 bytes.
+
+Alternation, @samp{\|}, is common but not portable.
+@c FIXME: I know Solaris is guilty, but I don't remember how.
+Anchors (@samp{^} and @samp{$}) inside groups are not portable.
+
+Nested groups are extremely portable, but there is at least one
+@command{sed} (System V/68 Base Operating System R3V7.1) that does not
+support it.
+
 Of course the option @option{-e} is portable, but it is not needed.  No
-valid @command{sed} program can start with a dash, so it does not help
+valid Sed program can start with a dash, so it does not help
 disambiguating.  Its sole usefulness is helping enforcing indenting as
 in:
 
@@ -5906,21 +5924,6 @@ Contrary to yet another urban legend, you may portably use @samp{&} in
 the replacement part of the @code{s} command to mean ``what was
 matched''.
 
-@command{sed} scripts should not use branch labels longer than 8
-characters and should not contain comments.
-
-@command{sed} input should have reasonably long lines, since some
-@command{sed} have an input buffer limited to 4000 bytes.
-
-Alternation, @samp{\|}, is common but not portable.
-
-Nested groups are extremely portable, but there is at least one
-@command{sed} (System V/68 Base Operating System R3V7.1) that does not
-support it.
-
-Anchors (@samp{^} and @samp{$}) inside groups are not portable.
-@c FIXME: I know Solaris is guilty, but I don't remember how.
-
 
 @item @command{sed} (@samp{t})
 @cindex @command{sed} (@samp{t})