[SOLVED] grep or egrep help

roopakl · 12-18-2012, 12:09 AM

Hi All,
I want to search particular date logs from /var/log/httpd/access.log file. For example log file having entries as below

Code:

tail -n2 /var/log/httpd/access.log
192.168.223.105 - - [18/Dec/2012:11:14:38 +0530] "GET /favicon.ico HTTP/1.1" 404 287 "-" "Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:16.0) Gecko/20120827 Firefox/16.0"
192.168.223.133 - - [18/Dec/2012:11:14:38 +0530] "GET /favicon.ico HTTP/1.1" 404 287 "-" "Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:16.0) Gecko/20120827 Firefox/16.0"

I tried

Code:

grep -i "18/Dec/12" /var/log/httpd/access.log
egrep -i "18/Dec/12" /var/log/httpd/access.log
egrep -i "*18/Dec/12*" /var/log/httpd/access.log
egrep "*18/Dec/12*" /var/log/httpd/access.log
egrep '*18/Dec/12*' /var/log/httpd/access.log
egrep -i *'18/Dec/12'* /var/log/httpd/access.log
egrep -i '*18/Dec/12*' /var/log/httpd/access.log

But showing nothing. So need your kind help.

roopakl · 12-18-2012, 01:25 AM

Sorry, I disturbed you all, Actually the mistake was from my side. I was trying

Code:

grep "18/Dec/12" /var/log/httpd/access.log

instead

Code:

grep "18/Dec/2012" /var/log/httpd/access.log

David the H. · 12-19-2012, 10:54 AM

Small mistakes like that can certainly trip you up!

Incidentally, this is wrong, even if you're using the right date format:

Code:

egrep -i "*18/Dec/12*" /var/log/httpd/access.log

grep uses regular expressions, not globbing (wildcard) patterns. While in globbing '*' has the meaning of "an unbroken string of characters of any type and length, including none", in regex it means "zero or more instances of the previous character". So on its own it's almost meaningless, and may even match something you don't want.

To get the wildcard behavior in regex you have to use ".*", with "." meaning "any character".

It's well worth taking the time to familiarize yourself with regex. Here are a few links for you:

http://mywiki.wooledge.org/RegularExpression
http://www.grymoire.com/Unix/Regular.html
http://www.regular-expressions.info/

And this link will give you a general overview of globbing (although it's actually written for the bash shell flavor of it and not everything mentioned is supported by other tools).

http://mywiki.wooledge.org/glob

roopakl · 12-19-2012, 11:12 AM

Thanks David the H.
I really appreciate your explanation skill but not only in this thread, also in your other threads.