From: Eric Blake <eblake@redhat.com>
Date: Thu, 5 May 2011 14:29:21 +0000 (-0600)
Subject: doc: document dash bug with positional parameters
X-Git-Tag: v2.68b~76
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2105ae97000c7c77442b3a788c90d8fee63bd2b3;p=thirdparty%2Fautoconf.git

doc: document dash bug with positional parameters

* doc/autoconf.texi (Shell Substitutions) <${10}>: Document
a pitfall with $10.

Signed-off-by: Eric Blake <eblake@redhat.com>
---

diff --git a/ChangeLog b/ChangeLog
index 14abf514..1fca7bbf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2011-05-05  Eric Blake  <eblake@redhat.com>
+
+	doc: document dash bug with positional parameters
+	* doc/autoconf.texi (Shell Substitutions) <${10}>: Document
+	a pitfall with $10.
+
 2011-04-27  Eric Blake  <eblake@redhat.com>
 
 	docs: document NetBSD join bug
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index b466e560..7ff693f5 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -15846,6 +15846,18 @@ $ @kbd{echo $@{10@}}
 bad substitution
 @end example
 
+Conversely, not all shells obey the Posix rule that when braces are
+omitted, multiple digits beyond a @samp{$} imply the single-digit
+positional parameter expansion concatenated with the remaining literal
+digits.  To work around the issue, you must use braces.
+
+@example
+$ @kbd{bash -c 'set a b c d e f g h i j; echo $10 $@{1@}0'}
+a0 a0
+$ @kbd{dash -c 'set a b c d e f g h i j; echo $10 $@{1@}0'}
+j a0
+@end example
+
 @item $@{@var{var}:-@var{value}@}
 @c Info cannot handle `:' in index entries.
 @ifnotinfo