multido 0.1.0

Useful utility to easily run a command in parallel and understand any failures that may have occurred

multido provides a simple command line utility for easily running a shell command multiple times in parallel. One of the most useful examples generally works like this:

$ multido "ssh %s uptime" host1 host2 host3
host1: 22:02:28 up 5 days,  2:52,  0 users,  load average: 0.05, 0.04, 0.05
host2: 22:02:27 up 5 days, 24 min,  0 users,  load average: 0.05, 0.03, 0.05
host3: 22:02:28 up 6 days, 48 min,  0 users,  load average: 0.01, 0.02, 0.05

Unlike say, xargs -P, multido will not just give up if there is a problem with one of the commands, instead it will output the STDERR to STDERR with the RC prepended to each line:

$ multido "ls /etc/%s" passwd missing sudoers
passwd: /etc/passwd
missing: RC1: ls: /etc/missing: No such file or directory
sudoers: /etc/sudoers

multido also accepts stdin from a pipe too, making for easy to chain commands:

$ echo -e "host1\nhost2\nhost3" | multido "ssh %s date"
host1: Mon Sep 17 22:08:40 UTC 2012
host2: Mon Sep 17 22:08:40 UTC 2012
host3: Mon Sep 17 22:08:40 UTC 2012

If you have a preferred grouping you would like the commands to be executed in there is a syntax to support grouping:

$ multido "echo %s; sleep 1" [ 'b1a' 'b1b' ] [ 'b2' ] [ 'b3a' 'b3b' 'b3c' ]
b1a: b1a
b1b: b1b
b2: b2
b3a: b3a
b3b: b3b
b3c: b3c

Or if you just want to limit to batches of N at a time there is syntax available to achieve that:

$ N=2; multido -P$N "echo %s; sleep 1" a b c
a: a
b: b
c: c