Running a list of commands

Problem

You want to run a list of commands in order, sometimes in parallel. Sometimes you want to run a command only if another command succeeds or fails.

Solution

To run more than one command in order, simply type each command in the order you want them to run, separating them with a semicolon ;

    echo 1; echo 2; echo 3;
    > 1
    > 2
    > 3

To run a command only if the previous ones succeed, we can use &&

    ls <file> && rm <file> -rf

To run a command only if the previous ones fail, we use ||

    ls file &> /dev/null || echo "File not exist"
    > File not exist

To run several commands in parallel, you can run them as background process using & then wait

process1 &
process2 &
process3 &
process4 &
wait
process5 &
process6 &
process7 &
process8 &
wait

If you want to make sure that all processes succeeds together, you can use npm package parallelshell

    parallelshell "echo 1" "echo 2" "echo 3"

References

• http://stackoverflow.com/questions/19543139/bash-script-processing-commands-in-parallel