topic Re: grep and "AND" in Operating System - Linux

grep and "AND"

Balaji N — Tue, 05 Aug 2003 19:46:17 GMT

hi gurus
am stuck with this for quite some time now. googling doesnt help.

let us say my file is like this
*****************************
#a
abcd
#abcd
abcd1
*******************************

i want to find out all occurances of abcd which doesnt have this comment.

i know this

grep -v ^# file | grep "abcd" file.

but is it possible to do this in a single grep.

something like this

grep -e (^#|abcd) file

will matach either of this pattern.

is there something will match both the pattern (the AND clause).

thanks for all the help. am stuck at this moment and bunnies for quick answers.
-balaji

Re: grep and "AND"

Steven E. Protter — Tue, 05 Aug 2003 20:08:29 GMT

grep abcd file.text | grep -v ^#

output:

abcd
abcd1

worked for me in HP-UX?

What about Linux? Or do I not understand the question?

SEP

Re: grep and "AND"

John Poff — Tue, 05 Aug 2003 20:16:04 GMT

Hi,

I got this to work:

grep "^abcd" file

but I don't think it is exactly what you are
looking for, as it will fail to find:

# abcd

SEP, the way you mentioned works but Balaji
is looking to do it with a single grep command.

JP

Re: grep and "AND"

Balaji N — Tue, 05 Aug 2003 20:35:24 GMT

hi SEP,
i am looking for that to be done in a single grep.

is there a way do it without piping in the output to grep.

-balaji

Re: grep and "AND"

Stuart Browne — Tue, 05 Aug 2003 22:59:10 GMT

This command should do it:

grep "^[^#]bcd" file

The [^#] is basically saying "not #".

But the leading ^ (outside of the []'s) will say that it needs to be at the start of the line, but it also takes up a character space.

This brings us to some more regular expression fun:

grep "^[^#]*abcd" file

will match properly as requested. The * obviously meaning '0 or more' of the previous atom (character not # which is at the start of a string)...

yay.. fun.. Ok, so I started in one direction, found the proper one, and couldn't be bothered re-typing the response ;P

Re: grep and "AND"

Steven E. Protter — Wed, 06 Aug 2003 00:20:30 GMT

I've tested the final solutions of all contestants and they all work.

I always love Stuart's answers
grep "^[^#]bcd"

output

abcd
abcd1

I knew it wasn't so easy as my answer. It would be nice to know however why two greps are a problem. Overhead? Or just looking for an elegant solution.

Apologies for my misunderstanding. Feel free to zero point both posts.

:-)

SEP

Re: grep and "AND"

John Meissner — Wed, 06 Aug 2003 16:05:06 GMT

i'd use

cat file | grep ^abcd

Re: grep and "AND"

Wouter Jagers — Thu, 07 Aug 2003 00:57:00 GMT

sed masters in being one process:

sed -n -e '/^#/d' -e '/abcd/p' < file

regards
Wouter