The FreeBSD Diary

Have you ever needed to do the same task on more than one machine at a time? If so, then clusterssh is the tool for you. From their homepage:

ClusterSSH is a tool for making the same change on multiple servers at the same time. The 'cssh' command opens an administration console and an xterm to all specified hosts. Any text typed into the administration console is replicated to all windows. All windows may also be typed into directly.

This tool is intended for (but not limited to) cluster administration where the same configuration or commands must be run on each node within the cluster. Performing these commands all at once via this tool ensures all nodes are kept in sync.

I found cssh very useful when I was setting up some jails, each of which was used for Bacula regression testing.

Using cssh is easy. First, install it:

cd /usr/ports/security/cssh
make install clean

This assumes you have x11/xterm installed (I did). Then run it:

cssh mysql41 mysql50 mysql51 mysql54

The following screen shot shows the above session opened and running with crontab -e:

The small window in the top left is cssh. This is where you type commands that will be echoed to each window. If you need to do something with just one window, click on it and type away. When you want to control all the session again, click on the cssh window.

This is something I will be using often.