GNU bug report logs - #25336

Previous Next

Full log

Message #10 received at 25336-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Zepp Lu <luzepu678 <at> gmail.com>, 25336-done <at> debbugs.gnu.org
Subject: Re: bug#25336:
Date: Mon, 2 Jan 2017 10:30:32 -0800

Zepp Lu wrote:

> $ printf '\x53\xef' | grep -aoP '\x53\xef'
> (no output, returns 1)
> $ printf '\x53\xc3\xaf' | grep -aoP '\x53\xef'
> Sï
> $ printf '\x53\xc3\xef' | grep -aoP '\x53\xef'
> (no output, returns 1)

I don't see a bug here. PCRE patterns like \xef match code points, not bytes, so 
the PCRE notation differs from the shell printf notation. If your locale uses 
UTF-8, the PCRE pattern \xef matches the Unicode character U+00EF LATIN SMALL 
LETTER I WITH DIAERESIS, which is represented by the byte pair C3 AF.

If you want \xef to match a single byte, run grep in a single-byte locale, e.g., 
set LC_ALL=C in the environment.

> grep (version 2.12-2) provided by Debian works just fine.

Actually, it's buggy in this area. Sometimes it can dump core.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.