Linux Blog

Using a custom Tomcat on Fedora

Filed under: Quick Linux Tutorials — TheLinuxBlog.com at 10:22 am on Wednesday, November 12, 2008

So, I hear you need to use Tomcat on Fedora eh? Not happy with the available Tomcat version from the repository? Well my friends you can add a custom Tomcat to Fedora and have it run as a service.

This post is somewhat related to: my Adding a service on Fedora post except this one is more specific to Tomcat. If you’d like more information on adding services to Fedora that is the place to look.

Here is the script that I have been using: (Read on …)

Snippet: Keeping SSH Running

Filed under: Quick Linux Tutorials,Shell Script Sundays — TheLinuxBlog.com at 12:53 am on Sunday, November 4, 2007

I wrote a post not so long back called Bringing The Internet Up After Failure that explained how I was restarting my network services after the internet went down.

Shortly after this I was remotely working when I thought it would be a good idea to restart my SSHD to enable X11 forwarding. After running the script that normally restarts the service I tried to reconnect. Unfortunately the service never restarted after being stopped. This is not a good situation for any one to be in so I added something like this to my cron along at the end of my network services script:

ps ax | grep \usr\/sbin\/sshd | grep Ss && echo “SSHD Running” || echo “Starting SSH”; sudo /etc/rc.d/rc.sshd start

The only difference between the version I am running and the version above is that I don’t echo anything out. All the command does is use the ps command and grep for usr/sbin/sshd then grep for the STAT field of sS. I do this because sshd shows up in the process list as shown below:

owen@the-linux-blog$ ps ax | grep sshd
3463 pts/0 R+ 0:00 grep sshd

The rest is self explanitory, it echo’s “SSHD Running” or sudo starts the SSHD.

If SSHD ever terminates on me or those of us who run this snippet we will be able to rightfully regain access to our systems, Hurray!

Bringing The Internet Up After Failure

Filed under: Shell Script Sundays — TheLinuxBlog.com at 9:58 pm on Sunday, September 9, 2007

This Shell Script Sunday is a short one but don’t let that fool you to the power of the shell. This script I wrote earlier in the week due to power spikes at the office. All of our equipment would stay powered on due to UPS’s but unfortunately something with the ISP was not staying on. Once the brownout occurred our router box would still have an IP and seem to be working but it wouldn’t. We had our suspicions about what piece of equipment it was but had no power to fix it. I would renew the IP from the ISP bring the public interface down by using eth0 down and then eth0 up but this was not successful. To fix it from the router I had to actually reset the network. This worked, but we have some services running at the office that I like to access from home. So to fix the problem I wrote a one liner to reset the network if the connection goes down.

ping -c 1 OurISP.com 2> /dev/null > /dev/null && echo > /dev/null || sudo /etc/rc.d/network restart

The techniques in this script are covered in Shell Scripting 101. All this does is ping OurISP.com one time and output the error & standard output to /dev/null. If the ping was successful it does nothing and if the ping failed then it restarts the network. To get it to repeat at an interval I just set it up as a cron job. This did the trick and I now do not have to worry about brownouts.