I have some problems with grep and BRE (Basic Regular Expressions).
According to my documentation, a caret which is not the first character in
a BRE matches a literal caret.

The following command should find all lines containing "xx^x":
grep "xx^x"

But it doesn't match lines containing "xx^x".

Whereas
grep ".x^x"
works fine. It matches "xx^x"

Could somebody explain to me why the first command isn't working as
expected.
I'm using grep (GNU grep) 2.5.1

Thanks for your
Daniel Mentz

On Mon, 21 Aug 2006 17:00:09 +0200, Daniel Mentz
<usenet@fire-of-desire.de> wrote:
> I have some problems with grep and BRE (Basic Regular Expressions).
> According to my documentation, a caret which is not the first character in
> a BRE matches a literal caret.
>
> The following command should find all lines containing "xx^x":
> grep "xx^x"
>
> But it doesn't match lines containing "xx^x".
>
> Whereas
> grep ".x^x"
> works fine. It matches "xx^x"
>
> Could somebody explain to me why the first command isn't working as
> expected.
> I'm using grep (GNU grep) 2.5.1
>
It looks to me like you have discovered a bug. xx\^x will also work.


--
We have nowhere else to go... this is all we have.
-- Margaret Mead

On Mon, 21 Aug 2006 11:22:20 -0400, Bill Marcum wrote:
> On Mon, 21 Aug 2006 17:00:09 +0200, Daniel Mentz
> <usenet@fire-of-desire.de> wrote:
>> The following command should find all lines containing "xx^x":
>> grep "xx^x"
>> But it doesn't match lines containing "xx^x".
> It looks to me like you have discovered a bug. xx\^x will also work.
Thanks for your reply. I submitted a bug report on http://savannah.gnu.org/
I also tried it on a Solaris box and it works there.

Daniel Mentz wrote:
> I have some problems with grep and BRE (Basic Regular Expressions).
> According to my documentation, a caret which is not the first character in
> a BRE matches a literal caret.
>
> The following command should find all lines containing "xx^x":
> grep "xx^x"
>
> But it doesn't match lines containing "xx^x".
>
> Whereas
> grep ".x^x"
> works fine. It matches "xx^x"
>
> Could somebody explain to me why the first command isn't working as
> expected.
> I'm using grep (GNU grep) 2.5.1
>
> Thanks for your
> Daniel Mentz

Using GNU grep 2.5.1:

syscjm@ayato:~$ grep "xx^x" << EOF
> xxx^
> ^xxxx
> xxaxx^xb
> xx^xstuff
> now is the time
> for all xx^x
> EOF
xxaxx^xb
xx^xstuff
for all xx^x
syscjm@ayato:~$


Certainly seems to work fine to me. Perhaps you could be
more specific about your problems.


Chris Mattern

On 2006-08-21, Chris Mattern wrote:
> Daniel Mentz wrote:
>> I have some problems with grep and BRE (Basic Regular Expressions).
>> According to my documentation, a caret which is not the first character in
>> a BRE matches a literal caret.
>>
>> The following command should find all lines containing "xx^x":
>> grep "xx^x"
>>
>> But it doesn't match lines containing "xx^x".
>>
>> Whereas
>> grep ".x^x"
>> works fine. It matches "xx^x"
>>
>> Could somebody explain to me why the first command isn't working as
>> expected.
>> I'm using grep (GNU grep) 2.5.1
>>
>> Thanks for your
>> Daniel Mentz
>
> Using GNU grep 2.5.1:
>
> syscjm@ayato:~$ grep "xx^x" << EOF
> > xxx^
> > ^xxxx
> > xxaxx^xb
> > xx^xstuff
> > now is the time
> > for all xx^x
> > EOF
> xxaxx^xb
> xx^xstuff
> for all xx^x
> syscjm@ayato:~$
>
>
> Certainly seems to work fine to me. Perhaps you could be
> more specific about your problems.

I see the same problem:

$ grep --version
grep (GNU grep) 2.5.1
$ grep "xx^x" << EOF
> xxx^
> ^xxxx
> xxaxx^xb
> xx^xstuff
> now is the time
> for all xx^x
> EOF
$


--
Chris F.A. Johnson, author <http://cfaj.freeshell.org>
Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
===== My code in this post, if any, assumes the POSIX locale
===== and is released under the GNU General Public Licence

On Mon, 21 Aug 2006 14:18:26 -0400, Chris Mattern wrote:

> Daniel Mentz wrote:
>> The following command should find all lines containing "xx^x":
>> grep "xx^x"
>>
>> But it doesn't match lines containing "xx^x".

>> I'm using grep (GNU grep) 2.5.1
> Using GNU grep 2.5.1:
>
> syscjm@ayato:~$ grep "xx^x" << EOF
> > xxx^
> > ^xxxx
> > xxaxx^xb
> > xx^xstuff
> > now is the time
> > for all xx^x
> > EOF
> xxaxx^xb
> xx^xstuff
> for all xx^x
> syscjm@ayato:~$
>
>
> Certainly seems to work fine to me. Perhaps you could be
> more specific about your problems.

I tried the command you provided on three different machines and I get a
different output (no output at all). Would you mind trying it on another
machine as well?

I also downloaded a vanilla version of GNU grep 2.5.1 and I'm getting the
same result.

[mentz@baobab src]$ ./grep "xx^x" << EOF
> xx^x
> EOF
[mentz@baobab src]$

Thanks
Daniel Mentz

Daniel Mentz wrote:
> On Mon, 21 Aug 2006 14:18:26 -0400, Chris Mattern wrote:
>
>
>>Daniel Mentz wrote:
>>
>>>The following command should find all lines containing "xx^x":
>>>grep "xx^x"
>>>
>>>But it doesn't match lines containing "xx^x".
>
>
>>>I'm using grep (GNU grep) 2.5.1
>>
>>Using GNU grep 2.5.1:
>>
>>syscjm@ayato:~$ grep "xx^x" << EOF
>> > xxx^
>> > ^xxxx
>> > xxaxx^xb
>> > xx^xstuff
>> > now is the time
>> > for all xx^x
>> > EOF
>>xxaxx^xb
>>xx^xstuff
>>for all xx^x
>>syscjm@ayato:~$
>>
>>
>>Certainly seems to work fine to me. Perhaps you could be
>>more specific about your problems.
>
>
> I tried the command you provided on three different machines and I get a
> different output (no output at all). Would you mind trying it on another
> machine as well?
>
> I also downloaded a vanilla version of GNU grep 2.5.1 and I'm getting the
> same result.
>
> [mentz@baobab src]$ ./grep "xx^x" << EOF
>
>>xx^x
>>EOF
>
> [mentz@baobab src]$
>

My test above was done on a Debian box with a fairly up-to-date Etch
distribution, using GNU grep 2.5.1 and GNU bash 3.1.14(1)-release.
A test on a Solaris 10 box with up-to-date patches, using Solaris grep
(both /usr/bin/grep and /usr/xpg4/bin/grep) and ksh (M-11/16/88i)
produced the same successful results. At the moment, to me, it looks
to me like a bug in GNU grep that Debian patched.


Chris Mattern

Chris Mattern wrote:
> Daniel Mentz wrote:
> > On Mon, 21 Aug 2006 14:18:26 -0400, Chris Mattern wrote:
> >
> >
> >>Daniel Mentz wrote:
> >>
> >>>The following command should find all lines containing "xx^x":
> >>>grep "xx^x"
> >>>
> >>>But it doesn't match lines containing "xx^x".
> >
> >
> >>>I'm using grep (GNU grep) 2.5.1
> >>
> >>Using GNU grep 2.5.1:
> >>
> >>syscjm@ayato:~$ grep "xx^x" << EOF
> >> > xxx^
> >> > ^xxxx
> >> > xxaxx^xb
> >> > xx^xstuff
> >> > now is the time
> >> > for all xx^x
> >> > EOF
> >>xxaxx^xb
> >>xx^xstuff
> >>for all xx^x
> >>syscjm@ayato:~$
> >>
> >>
> >>Certainly seems to work fine to me. Perhaps you could be
> >>more specific about your problems.
> >
> >
> > I tried the command you provided on three different machines and I get a
> > different output (no output at all). Would you mind trying it on another
> > machine as well?
> >
> > I also downloaded a vanilla version of GNU grep 2.5.1 and I'm getting the
> > same result.
> >
> > [mentz@baobab src]$ ./grep "xx^x" << EOF
> >
> >>xx^x
> >>EOF
> >
> > [mentz@baobab src]$
> >
>
> My test above was done on a Debian box with a fairly up-to-date Etch
> distribution, using GNU grep 2.5.1 and GNU bash 3.1.14(1)-release.
> A test on a Solaris 10 box with up-to-date patches, using Solaris grep
> (both /usr/bin/grep and /usr/xpg4/bin/grep) and ksh (M-11/16/88i)
> produced the same successful results. At the moment, to me, it looks
> to me like a bug in GNU grep that Debian patched.
>
>
> Chris Mattern

On a Aix 4.3.3 ksh: just FYI,
$ more go
echo "A"
grep "xx^x" << EOF
xxx^
^xxxx
xxaxx^xb
xx^xsstuff
now is the time
for all xx^x
EOF

$
$ ksh go
A
xxaxx^xb
xx^xsstuff
for all xx^x

JB