topic Re: Grep on fixed value in Operating System - HP-UX

Grep on fixed value

dev44 — Wed, 23 Sep 2009 11:17:19 GMT

Hi,

I have a file like this:

hello
hello123
hello345
hello678

I want to grep on "hello" and only output the first line. So I want to grep for "hello" as a fixed or absolute value.

Re: Grep on fixed value

James R. Ferguson — Wed, 23 Sep 2009 11:22:20 GMT

Hi:

Anchor the pattern:

# grep ^hello$ file

Regards!

...JRF...

Re: Grep on fixed value

dev44 — Wed, 23 Sep 2009 11:26:55 GMT

It came back with no ouput at all.

Re: Grep on fixed value

James R. Ferguson — Wed, 23 Sep 2009 11:32:12 GMT

Hi:

> It came back with no output at all.

Then there is probably whitespace before and/or after the "hello" token. This is easy to fix:

# perl -ne 'm{^\s*hello\s*$} and print' file

The '\s' denotes whitespace (spaces, tabs). The anchors (^ and $) make sure that the spaces are the ONLY characters preceding or trailing the token to match.

Regards!

...JRF...

Re: Grep on fixed value

TTr — Wed, 23 Sep 2009 11:41:23 GMT

After 11.11 the grep command has the -w option which greps for whole word only and will work if the work hello had leading and trailing spaces as well.
grep -w hello hello-file

Re: Grep on fixed value

Dennis Handly — Wed, 23 Sep 2009 14:01:57 GMT

>JFR: Anchor the pattern: grep ^hello$ file

Instead of doing that you could use -x.
Since you don't have a pattern you can just use fgrep -x. Except as JRF said, you seem to have trailing spaces, so you can use grep -w as TTr mentioned.