topic Re: Regular expression result in Operating System - HP-UX

Regular expression result

Sébastien N — Tue, 19 Aug 2003 12:16:24 GMT

Hi,

I write :
echo "TRU 123ZER" | sed 's/.*\([0-9][0-9]*\).*/\1/'
and the result is "3".

Shouldn't it be "123" ?*

Thanx.

Re: Regular expression result

Umapathy S — Tue, 19 Aug 2003 12:33:53 GMT

Sebastian,
I think there should a space between first .*

echo "TRU 123ZER" | sed 's/.* \([0-9][0-9]*\).*/\1/'

HTH,
Umapathy

Re: Regular expression result

Brian Bergstrand — Tue, 19 Aug 2003 12:46:45 GMT

You are running into RE's "match the most I can" policy. You need to break qualify your requirements more.

This should work better:

echo "TRU 123ZER" | sed 's/[^0-9]*\([0-9][0-9]*\).*/\1/'

HTH.

Re: Regular expression result

Sébastien N — Tue, 19 Aug 2003 12:58:43 GMT

Both are working.
But I don't understand why...

Thanx a lot.

what does HTH mean ?

Re: Regular expression result

Umapathy S — Tue, 19 Aug 2003 13:23:50 GMT

Sebastian,
As Brian said, "match the most I can" is done by .* which expands to a char followed by any number of chars that include a space also.
The backslashed number represents the group of chars within the braces. Here in your exp you match only the numbers with your braces and thats get printed.
Without spaces all the numbers except 3 is gathered by the first .*.

HTH means Hope This Helps.

HTH,
Umapathy