How can I automate running commands remotely over SSH to multiple servers in parallel?

Question

I\'ve searched around a bit for similar questions, but other than running one command or perhaps a few command with items such as:

ssh user@host -t sudo su -         


        

Answer 1

The issue of how to run commands on many servers at once came up on a Perl mailing list the other day and I'll give the same recommendation I gave there, which is to use gsh:

http://outflux.net/unix/software/gsh

gsh is similar to the "for box in box1_name box2_name box3_name" solution already given but I find gsh to be more convenient. You set up a /etc/ghosts file containing your servers in groups such as web, db, RHEL4, x86_64, or whatever (man ghosts) then you use that group when you call gsh.

[pdurbin@beamish ~]$ gsh web "cat /etc/redhat-release; uname -r"
www-2.foo.com: Red Hat Enterprise Linux AS release 4 (Nahant Update 7)
www-2.foo.com: 2.6.9-78.0.1.ELsmp
www-3.foo.com: Red Hat Enterprise Linux AS release 4 (Nahant Update 7)
www-3.foo.com: 2.6.9-78.0.1.ELsmp
www-4.foo.com: Red Hat Enterprise Linux Server release 5.2 (Tikanga)
www-4.foo.com: 2.6.18-92.1.13.el5
www-5.foo.com: Red Hat Enterprise Linux Server release 5.2 (Tikanga)
www-5.foo.com: 2.6.18-92.1.13.el5
[pdurbin@beamish ~]$

You can also combine or split ghost groups, using web+db or web-RHEL4, for example.

I'll also mention that while I have never used shmux, its website contains a list of software (including gsh) that lets you run commands on many servers at once. Capistrano has already been mentioned and (from what I understand) could be on that list as well.