2006-05-22  Paul Eggert  <address@hidden>,
	    Ralf Wildenhues  <address@hidden>,
	    Stepan Kasal  <address@hidden>

	* doc/autoconf.texi (Particular Programs): Do not promise that
	we always prefer the GNU version of the program, and that we
	search according to PATH; both rules can have exceptions.
	Update description of AC_PROG_SED.
	(Limitations of Usual Tools) <sed>: Mention script length
	limitations with some of the sed implementations on Solaris.

Index: doc/autoconf.texi
===================================================================
RCS file: /cvsroot/autoconf/autoconf/doc/autoconf.texi,v
retrieving revision 1.1019
diff -u -r1.1019 autoconf.texi
--- doc/autoconf.texi	22 May 2006 10:28:34 -0000	1.1019
+++ doc/autoconf.texi	22 May 2006 11:15:20 -0000
@@ -3458,32 +3458,25 @@
 @defmac AC_PROG_GREP
 @acindex{PROG_GREP}
 @ovindex GREP
-On AIX the default @code{grep} silently truncates long lines on the
-input before matching.  On Solaris, @code{/usr/bin/grep} does not
-understand the @option{-e} option.  On NeXT, @code{grep} understands only a
-single @option{-e} option.  This macro looks for @sc{gnu} Grep or
-else the best available @code{grep} or @code{ggrep} in the user's
address@hidden which accepts the longest input lines possible, and which
-accepts and respects multiple @option{-e} options.  Set the
-output variable @code{GREP} to whatever is chosen.
+Look for the best available @code{grep} or @code{ggrep} which accepts the
+longest input lines possible, and which handles multiple @option{-e} options.
+Set the output variable @code{GREP} to whatever is chosen.
 @end defmac
 
 @defmac AC_PROG_EGREP
 @acindex{PROG_EGREP}
 @ovindex EGREP
-Check whether @code{$GREP -E} works, or else search the user's
address@hidden for @code{egrep}, and @code{gegrep}, in that order, and set
-output variable @code{EGREP} to the one that accepts the longest input
-lines.
+Check whether @code{$GREP -E} works, or else search for @code{egrep}, and
address@hidden, in that order, and set output variable @code{EGREP} to the one
+that accepts the longest input lines.
 @end defmac
 
 @defmac AC_PROG_FGREP
 @acindex{PROG_FGREP}
 @ovindex FGREP
-Check whether @code{$GREP -F} works, or else search the user's
address@hidden for @code{fgrep}, and @code{gfgrep}, in that order, and set
-output variable @code{FGREP} to the one that accepts the longest input
-lines.
+Check whether @code{$GREP -F} works, or else search for @code{fgrep}, and
address@hidden, in that order, and set output variable @code{FGREP} to the one
+that accepts the longest input lines.
 @end defmac
 
 @defmac AC_PROG_INSTALL
@@ -3632,9 +3625,9 @@
 @defmac AC_PROG_SED
 @acindex{PROG_SED}
 @ovindex SED
-Set output variable @code{SED} to a Sed implementation on @env{PATH} that
-truncates as few characters as possible.  If @sc{gnu} Sed is found,
-use that instead.
+Set output variable @code{SED} to a Sed implementation that conforms to Posix
+and does not have arbitrary length limits.  If no acceptable Sed is found, an
+error is reported.
 @end defmac
 
 @defmac AC_PROG_YACC
@@ -13211,6 +13204,10 @@
 (not counting @samp{:} commands) and
 48 labels, which can not be circumvented by using more than one script
 file.  It can execute up to 19 reads with the @samp{r} command per cycle.
+Solaris @command{/usr/ucb/sed} has a limit of about 6000 bytes for the
+internal representation of the sed script, which can not be circumvented
+using more than one script file, and it fails with longer scripts.
+Moreover, Solaris @command{/usr/xpg4/bin/sed} dumps core with long scripts.
 
 Avoid redundant @samp{;}, as some @command{sed} implementations, such as
 address@hidden 1.4.2's, incorrectly try to interpret the second