The sys admin's daily grind: parallel SSH

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Article from Issue 97/2008
Author(s):

Parallel SSH is the name of an easy-to-configure tool that our resident sys admin, Charly, now routinely deploys whenever he needs to launch the same programs, copy the same files, or kill the same processes simultaneously on multiple computers.

I am writing from a Linux seminar in the Linuxhotel in Essen, Germany. The environment here comprises four Xen virtualized machines. Identical changes to all cluster nodes are a regular requirement, which is a pain, but I have a utility up my sleeve: parallel SSH [1]. Pssh relies on the SSH agent running, so I'll take care of that first:

ssh-agent
ssh-add

After I enter the pass phrase for my SSH key, the AAH agent ensures that nobody will ask me for it, at least not during the current session. Next, I need a text file in which I add the IP addresses of the servers for which I need to set up simultaneous connections, so I'll start by adding three addresses to server.txt:

[...]

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