Ubuntu
grep package

grep -w doesn't always grab whole words - broken multibyte support

Bug #274221 reported by Rusty Russell
4
Affects Status Importance Assigned to Milestone
grep
Unknown
Unknown
grep (Ubuntu)
Confirmed
Undecided
Unassigned

Bug Description

Binary package hint: grep

1)
rusty@vivaldi:~$ lsb_release -rd
Description: Ubuntu 8.04.1
Release: 8.04

2) rusty@vivaldi:~$ apt-cache policy grep
grep:
  Installed: 2.5.3~dfsg-3
  Candidate: 2.5.3~dfsg-3
  Version table:
 *** 2.5.3~dfsg-3 0
        500 http://au.archive.ubuntu.com hardy/main Packages
        100 /var/lib/dpkg/status

3) Only whole words returned. There were a couple of spurious results in a large grep. Example file (from Linux kernel) is enclosed, and as you can see, piping through same grep expression again "fixes" the problem.

4) rusty@vivaldi:~$ grep -w alloca devel/kernel/linux-2.6/kernel/pid.c
 * Generic pidhash and scalable, time-bounded PID allocator
rusty@vivaldi:~$ grep -w alloca devel/kernel/linux-2.6/kernel/pid.c | grep -w alloca
rusty@vivaldi:~$

See original description
Revision history for this message
Rusty Russell (rusty-rustcorp) wrote :
Revision history for this message
Jean-Baptiste Lallement (jibel) wrote :

Thanks for your report. This is reproducible in Intrepid. I suspect that this is one of those multibyte bugs of grep.

Does it work correctly with the following command:
LANG=C grep -w alloca kernel/pid.c

Can you post the output of the command : locale

Thanks in advance.

Changed in grep:
status: New → Incomplete
Revision history for this message
Rusty Russell (rusty-rustcorp) wrote :

Yes, LANG=C fixes it.

rusty@vivaldi:~/devel/kernel/patches/linux-2.6$ LANG=C grep -w alloca kernel/pid.c
rusty@vivaldi:~/devel/kernel/patches/linux-2.6$ grep -w alloca kernel/pid.c
 * Generic pidhash and scalable, time-bounded PID allocator
rusty@vivaldi:~/devel/kernel/patches/linux-2.6$ locale
LANG=en_AU.UTF-8
LC_CTYPE="en_AU.UTF-8"
LC_NUMERIC="en_AU.UTF-8"
LC_TIME="en_AU.UTF-8"
LC_COLLATE="en_AU.UTF-8"
LC_MONETARY="en_AU.UTF-8"
LC_MESSAGES="en_AU.UTF-8"
LC_PAPER="en_AU.UTF-8"
LC_NAME="en_AU.UTF-8"
LC_ADDRESS="en_AU.UTF-8"
LC_TELEPHONE="en_AU.UTF-8"
LC_MEASUREMENT="en_AU.UTF-8"
LC_IDENTIFICATION="en_AU.UTF-8"
LC_ALL=

Revision history for this message
Jean-Baptiste Lallement (jibel) wrote :

Thanks for confirming.
We'll take a look.

Changed in grep:
status: Incomplete → Confirmed
description: updated
Revision history for this message
Jean-Baptiste Lallement (jibel) wrote :

this is a strange bug.

only grep -w alloca pid.c returns a wrong result on this particular string. Results returned with words "alloc" or "allocat" are corrects.

Do you have other examples in order to try to figure out a pattern to reproduce this issue ?

Thanks for your help.

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