George Hubka

Ever wonder how to find out what robots/crawlers have visited your site? If you don’t have robust log analyzer there is another way. If you are using apache there is a simple way from the command line to figure out how as been visiting.
grep robots.txt /etc/httpd/domlogs/bumideas.com|awk -F ‘”‘ ‘{print $6}’|sort -k 1|uniq -c
What […]

Ever find that you need to do a bulk/mass replacement of strings in a file on a linux server?  I ran into a situation where I needed to change a website from using persistent connections to mysql to normal.  This involved changing mysql_pconnect to mysql_connect.  Using grep, There were about 5 files to change.
Of course […]

Just surfing for fun today and came across a quick and easy tutorial for securing your linux server.  While not the end all for security, it sure is a great start.
http://mysql-apache-php.com/basic-linux-security.htm

From the internet, and slightly adjusted for a linux system… [http://www.kalab.com/freeware/cron/cron.htm]
The Crontab file
Each line of CRONTAB has the following structure:

Position:     Values:
Minute     0-59
Hour     0-23
Day     1-31
Month     1-12
Day of week     0-6 (0=Sunday, 1=Monday, …, 6=Saturday)
Instead of minute, hour, day, month or day of week it’s also possible […]

Mod_security is an awesome tool to scan query strings for malicious content…blocking it before it ever enters execution.
One of the best resources I have ever found to get some mod_security rules. They have both rules for versions 1 and 2. These rules block hundreds of attempts on my server every day.
http://www.gotroot.com/downloads/ftp/mod_security/rules.conf

How do you get a list of all the open files on linux?  There is a simple command that can give you all the information you need.
lsof
There are several helpful options to this command…
lsof by itself will give you all the open files.  pipe this through grep to find what you are looking for.
lsof -p […]

Here is another nugget from the mysql world.
Mysql has a built in logger for tracking down those queries that are long running queries. Technically mysql likes to call them “slow queries”
1. Login to your server as root
2. Open my.cnf with your favorite editor. Example:
[…]

3ware is a pretty common controller in linux boxes, there is a command utility tw_cli to check the status. You can automate the checking via a simple bash script that you can put into your cron. here is some code
#!/bin/bash
com=`/path_to_ tw_cli/tw_cli info c0 u0 status | awk ‘{print $4}’`
echo $com
if [ “$com” = […]

here is a clipping from the MySQL manual regarding the query cache to help your website performance.
mysql> SHOW VARIABLES LIKE ‘query_cache_size’;
+——————+——-+
| Variable_name | Value |
+——————+——-+
| query_cache_size | 41984 |
+——————+——-+
For the query cache to actually be able to hold any query results, its size must be set larger:
mysql> SET GLOBAL query_cache_size = 1000000;
Query […]

Looking to see what has changed on your linux server lately? This command will find files changed in the last 10 days
find ./ -type f -mtime -10 -exec ls -al {} \;