This post comes from my ever-growing file of ‘how the hell did I not know that’ issues.

On the cluster at work we have a bunch of machines with names like mysite12 or mysite237. So quite often I’m writing shell scripts to loop through all these boxes to get info. So I do something like this:

for number in `seq 12 256`
do
    node=mysite$number
    echo $node
done

Which produces

mysite12
mysite13
.....
mysite256

It occurred to me today that this is such a staggeringly common thing to do that seq probably has a way of doing it already. Sure enough after reading the man page it turns out that you can hand seq a PRINTF style format command. So I can create my node names purely in seq

for node in `seq -f "mysite%g" 12 255"
do
    echo $node
done


mysite12
mysite13
....
mysite255

How has it taken me ten years to work that out?