topic Re: Grepping issues.. in Operating System - Linux

Grepping issues..

Patrick Ware_1 — Wed, 27 Feb 2008 19:59:38 GMT

Hello,

I found another problem with my disk-adding script today. When looking for disks, I use grep.
When I grep for the following disk sizes:

5242880

I also pick up these as well:
524288000

How do I specifically pick out one or the other, using grep, without resorting to the -v option?

If I can't use grep, I'll have to totally revamp the script...

Re: Grepping issues..

James R. Ferguson — Wed, 27 Feb 2008 20:12:45 GMT

Hi Patrick:

You need to anchor your regular expression or modify it to fit the context you want to match.

For example:

# grep " 5242880 "

...would find matches that are bounded by a space on either side.

# grep "^5242880$"

...would demand that the string matched only if it was anchored to the beginning (^) and the end ($) of the line.

Regards!

...JRF...

Re: Grepping issues..

Patrick Ware_1 — Wed, 27 Feb 2008 20:47:07 GMT

Thanks for your reply. One more question:
I set the disk sizes to a variable called $SIZE. How would it work with a variable?

Re: Grepping issues..

James R. Ferguson — Wed, 27 Feb 2008 20:52:11 GMT

Hi (again) Patrick:

# VAR=5242880
# echo " 5242880 "|grep " ${VAR} "
5242880

That is, reference the variable just like you would when you interpolate it the shell. Notice that is is good practive to encapsulate the variable name in curly braces as shown.

Regards!

...JRF...

Re: Grepping issues..

Patrick Ware_1 — Wed, 27 Feb 2008 21:18:18 GMT

I am not understanding.
Here is an example of the what I am doing:

http://www.unix.com/showthread.php?p=302171123&posted=1#post302171123

Re: Grepping issues..

Patrick Ware_1 — Wed, 27 Feb 2008 21:26:59 GMT

grep -w worked like a charm.

Thanks to all!

I am always open to better solutions.

Re: Grepping issues..

James R. Ferguson — Wed, 27 Feb 2008 21:38:12 GMT

Hi (again):

Patrick, why is this post a VERBATIM copy from another forum site? INCLUDING someone else's suggestion to use the '-w' switch of grep !!!

...JRF...

Re: Grepping issues..

Patrick Ware_1 — Wed, 27 Feb 2008 22:04:13 GMT

I asked the same question over there. I always go back and post what worked for me.

Re: Grepping issues..

Dennis Handly — Thu, 28 Feb 2008 05:39:14 GMT

>grep -w worked like a charm.
>I am always open to better solutions.

That's what I would have suggested.