docs: document dash bug in <>

* doc/autoconf.texi (File Descriptors): Dash 0.5.5 truncates on
<>; at least this was fixed in dash 0.5.6.

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

diff --git a/ChangeLog b/ChangeLog
index 9217438ca914de11bfb87e668f2f657557d092cd..34b3be42ec5d306292f6e36c63fd6a71ec13d843 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-10-20  Eric Blake  <eblake@redhat.com>
+
+       docs: document dash bug in <>
+       * doc/autoconf.texi (File Descriptors): Dash 0.5.5 truncates on
+       <>; at least this was fixed in dash 0.5.6.
+
 2010-10-12  Ralf Wildenhues  <Ralf.Wildenhues@gmx.de>
 
        tests: avoid AC_CACHE_CHECK test failure with dash.

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index b9570834e1c48e8ec35c950af750158a150291b0..adbdded902194fe94f4508c01788cf4f6e7cb94c 100644 (file)
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -15060,6 +15060,18 @@ $ @kbd{echo hi >&5}
 bash: echo: write error: Communication error on send
 @end example
 
+@noindent
+Furthermore, versions of @command{dash} before 0.5.6 mistakenly truncate
+regular files when using @samp{<>}:
+
+@example
+$ @kbd{echo a > file}
+$ @kbd{bash -c ': 1<>file'; cat file}
+a
+$ @kbd{dash -c ': 1<>file'; cat file}
+$ rm a
+@end example
+
 When catering to old systems, don't redirect the same file descriptor
 several times, as you are doomed to failure under Ultrix.