I have an array with hostnames and I want to execute an other script with all the hostnames parallel. At first I did it iterative with a for-loop. But I want it parallel and I used the wait-command, but then I can't have dynamic number of hosts.
./sub.sh ${arr[0]} &
./sub.sh ${arr[1]} &
./sub.sh ${arr[2]}
wait
Now I need a function which with I can execute all the elements of the array. Do you have any solution for me?
With GNU Parallel like this:
# Generate test data
arr=($(seq 10))
# Check it looks good
echo "${arr[@]}"
1 2 3 4 5 6 7 8 9 10
# Process all elements of the array - just using "echo"
parallel -k echo {} ::: "${arr[@]}"
1
2
3
4
5
6
7
8
9
10
Other useful options, for parallel parameters:
-j N will run N jobs at a time--progress will show a progress bar-k will keep the outputs in order--tag will tag outputs (according to host in your case) In case the above is not clear in how it applies to your specific example, I am suggesting you do:
parallel --tag -k ./sub.sh {} ::: "${arr[@]}"
Try the below:
for host in "${arr[@]}" ; do
./sub.sh "$host" &
done
# wait for the background processes to finish
wait
