Question

I have a bash script that generates a vector of running Jobs on a cluster. Example:

Vector = [1.cluster 2.cluster 3.cluster]

I need to update this script to keep record of this Jobs. Normally I would do:

qstat jobnumber.cluster

My background is python and in python I could do something like:

map(qstat, Vector)

and this would return me a vector with the function return value for all vector entries. So the question is: Can I apply a function to a vector in bash and get a vector back?

Answer 1

Here’s the bash equivalent of the Pythonic code result = [qstat(cluster) for cluster in Vector].

If you’re using a bash array:

result=() # or declare -a result
for cluster in ${Vector[@]}; do
  result=("${result[@]}" "$(qstat $cluster)") # or result+=($(qstat $cluster))
done

The difference between the two ways of appending to the array are that the first explicitly expands the array to add a new element, while the second creates a new array with the new element to add it to the end. That’s because bash doesn’t have an equivalent to Python’s extend method.

If you’re using an IFS-separated string:

result=""
for cluster in $Vector; do
  result="${result} $(qstat cluster)"
done