Re: [PATCH] doc: detail inconsistencies in sed word boundary handling

On 01/11/16 13:46, Eric Blake wrote:
> On 10/30/2016 12:01 PM, Pádraig Brady wrote:
>> * doc/autoconf.texi (Limitations of usual tools): Display a
>> table showing where the various syntaxes for word boundaries
>> are supported.
>> ---
>>  doc/autoconf.texi | 12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/doc/autoconf.texi b/doc/autoconf.texi
>> index 4be1f70..2e4b7ba 100644
>> --- a/doc/autoconf.texi
>> +++ b/doc/autoconf.texi
>> @@ -19666,6 +19666,18 @@ $ @kbd{echo abc | busybox sed '/a\(b\)c/ s/a\(b\)c/\1/'}
>>  b
>>  @end example
>>  
>> +Portable scripts should be aware of the inconsistencies and
>> +options for handling word boundaries.
>> +
>> +@example
>> +                \<      \b      [[:<:]]
>> +Solaris 10      yes     no      no
>> +Solaris XPG4    yes     no      error
>> +NetBSD 5.1      no      no      yes
>> +FreeBSD 9.1     no      no      yes
>> +GNU             yes     yes     error
>> +busybox         yes     yes     error
>> +@end example
> 
> It might be nice to add Cygwin to the list, although I don't know if one
> row is sufficient.  It bases its regex engine on BSD code but adds an
> extension for \< and \>; but depending on whether a program uses the
> libc regex or its own, you can get GNU behavior (that is, Cygwin grep
> supports \< and \b but not [[:<:]] because it uses gnulib and bypasses
> native regex; while a native application supports [[:<:]] and \< but not
> \b because of the BSD heritage plus cygwin extension).

Interesting, re cygwin, though here we're considering sed,
which would fall under GNU I think?
I've updated the attached with the note about POSIX.

(I don't have commit access to this repo)

thanks,
Pádraig

From a5333e422d20f0e43407919ae1d5b46ebefc9c4e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A1draig=20Brady?= <[email protected]>
Date: Sun, 30 Oct 2016 16:58:09 +0000
Subject: [PATCH] doc: detail inconsistencies in sed word boundary handling

* doc/autoconf.texi (Limitations of usual tools): Display a
table showing where the various syntaxes for word boundaries
are supported.
---
 doc/autoconf.texi | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index 4be1f70..3e3a894 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -19666,6 +19666,18 @@ $ @kbd{echo abc | busybox sed '/a\(b\)c/ s/a\(b\)c/\1/'}
 b
 @end example
 
+Portable scripts should be aware of the inconsistencies and options for
+handling word boundaries, as these are not specified by POSIX.
+
+@example
+                \<      \b      [[:<:]]
+Solaris 10      yes     no      no
+Solaris XPG4    yes     no      error
+NetBSD 5.1      no      no      yes
+FreeBSD 9.1     no      no      yes
+GNU             yes     yes     error
+busybox         yes     yes     error
+@end example
 
 @item @command{sed} (@samp{t})
 @c ---------------------------
-- 
2.5.5