I recently had to install a couple of squid servers to act as reverse proxies for a webcluster. You can teach the squid server to stand in between in the end users and the webservers, and to store all the static content ( .jpg .flv .css .htm for example ) in the RAM. This saves a lot of I/O and bandwidth on the webservers, and it can really speeds up a site. And the end of the road the webservers' load dropped with 92%. But before all this worked, I had to run through a massive config file and since the squid config file is their manual at the same time, it's about 5000 lines long. So I had to find out a way to filter only the important settings from the config file.

This is what i came up with:

cat /etc/squid/squid.conf | egrep -v "(^#.*|^$)"

Explained

egrep -v      means leave the following out
^#.*          means patterns that begin with a #
|             means or
^$            means patterns that are empty

Updates

update #1

Thanks to an insightfull comment by Darwin Award Winner on this article, here's a version that would also filter comments with spaces before the #, such as comments that are indented with code blocks:

cat /etc/squid/squid.conf | egrep -v "^\s*(#|$)"

Thanks Darwin!

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tags: linux, cat, comments, squid, config file
category: Howto - System
read: 6,397 times

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Comments

#5. Kevin on 18 March 2009

Member avatar: Kevin @ Bash: Point taken. Though there are two points to be made as well:

- The consistent use of cat can be a good habit to ensure you never modify a file by accident.
- I doubt the extra process will have serious impact on my machine's performance. If it does, it's time for a new machine :)

#4. Bash on 17 March 2009

Useless use of cat award!

http://sial.org/howto/shell/useless-cat/

#3. aptgetupdate.de on 31 July 2007

Default avatar:aptgetupdate.de Thanks.

#2. Kevin on 31 July 2007

@Darwin Award Winner: Those are great suggestions, thanks! I will update the article.

#1. Darwin Award Winner on 31 July 2007

Default avatar:Darwin Award Winner I would suggest "^\s*(#|$)" as the pattern, since this would also filter comments with spaces before the #, such as comments that are indented with code blocks.

If you also wanted to remove comments at the ends of lines, you could pipe the output through sed 's/\s+#.*$//'

... [more] cat /etc/squid/squid.conf | egrep -v "^\s*(#|$)" | sed -e 's/\s+#.*$//'

You could create a script /usr/local/bin/conconf (catconf as in cat config files, or make up a more creative name) with the following contents (remember to make it executable):

#!/bin/sh
cat "$@" | egrep -v "^\s*(#|$)" | sed -e 's/\s+#.*$//'