Run parallel multiple commands at once in the same terminal

This bash script is for N parallel threads. Each argument is a command.

trap will kill all subprocesses when SIGINT is catched.
wait $PID_LIST is waiting each process to complete. When all processes have completed, the program exits.

#!/bin/bash

for cmd in "$@"; do {
  echo "Process \"$cmd\" started";
  $cmd & pid=$!
  PID_LIST+=" $pid";
} done

trap "kill $PID_LIST" SIGINT

echo "Parallel processes have started";

wait $PID_LIST

echo
echo "All processes have completed";

Save this script as parallel_commands and make it executable.
This is how to use this script:

parallel_commands "cmd arg0 arg1 arg2" "other_cmd arg0 arg2 arg3"

Example:

parallel_commands "sleep 1" "sleep 2" "sleep 3" "sleep 4"

Start 4 parallel sleep and waits until "sleep 4" finishes.

Based on comment of @alessandro-pezzato. Run multiples commands by using & between the commands.

Example:

$ sleep 3 & sleep 5 & sleep 2 &

It's will execute the commands in background.

Use GNU Parallel:

(echo command1; echo command2) | parallel
parallel ::: command1 command2

To kill:

parallel ::: command1 command2 &
PID=$!
kill -TERM $PID
kill -TERM $PID

Reference to gnu.org site.

It can be done with simple Makefile:

sleep%:
        sleep $(subst sleep,,$@)
        @echo $@ done.

Use -j option.

$ make -j sleep3 sleep2 sleep1
sleep 3
sleep 2
sleep 1
sleep1 done.
sleep2 done.
sleep3 done.

Without -j option it executes in serial.

$ make -j sleep3 sleep2 sleep1
sleep 3
sleep3 done.
sleep 2
sleep2 done.
sleep 1
sleep1 done.

You can also do dry run with `-n' option.

$ make -j -n sleep3 sleep2 sleep1
sleep 3
sleep 2
sleep 1