Logical all/any in bash

Question

I want to run a series of tests (each on a different PID), and derive a successful status only if all tests exit successfully. Something like

check $PID1 && check $PID2 && check $PID3

but for an indeterminate number of tests. How can I accomplish this?

Answer 1

That shouldn't be too hard to write out as a loop:

pids=(1025 3425 6474)
check_all() {
    for pid in "$@"; do
        if ! check "$pid"; then
            return 1
        fi
    done
}
check_all "${pids[@]}"

Like the chain of commands linked with &&, the function will stop on the first failing check.

Though do note that I replaced your variables PID1, PID2 etc. with a single array. Bash could iterate over variables whose names start with a particular string, but arrays are just more convenient. (Unless those variables come from the outside of the script through the environment where you can't pass proper arrays.)

Also, I hard-coded the check command in the loop here. You could pass distinct commands for the function to run, but that's ripe with issues with word splitting and quote handling. (See here and here.)

Answer 2

You could put it in a subshell with exit-on-error ( -e ):

pids=(1025 3425 6474)
(
    set -e
    for pid in "${pids[@]}"; do
        check "$pid"
    done
)
echo $?

Alternatively, you can use || exit 1 instead of set -e:

pids=(1025 3425 6474)
(
    for pid in "${pids[@]}"; do
        check "$pid" || exit 1
    done
)
echo $?

Answer 3

Maybe:

parallel -j0 check ::: $pid1 $pid2 $pidN &&
  echo all succeeded
parallel -j0  '! check' ::: $pid1 $pid2 $pidN &&
  echo all failed
parallel -j0 --halt soon,success=1 check ::: $pid1 $pid2 $pidN &&
  echo one succeeded
parallel -j0 --halt soon,fail=1 check ::: $pid1 $pid2 $pidN ||
  echo one failed

It will run the checks in parallel. Replace soon with now if you want running checks to be killed as soon as we know the result.

If you have the PIDs as output from a pipe (one per line):

pid_generator | parallel -j0 check && echo all succeeded

parallel gives one value to check and runs as many check as possible in parallel (-j0).

If the server does not have parallel installed, run this on a machine that has parallel installed:

parallel --embed > new_script

Edit new_script (the last 5 lines) and copy the script to the server.

Answer 4

A simple function could test each argument; if any fail, return from the function with a non-zero code:

#!/bin/sh

testall() {
  for test
  do
    sh -c "$test" || return 1
  done
}

With some example tests:

$ testall "echo 1" "echo 2" "false" && echo all OK
1
2
$ testall "echo 1" "echo 2" "echo 3" && echo all OK
1
2
3
all OK
$ testall && echo all OK
all OK