You can do something like:

max_processes=20
for ((i=0; i<$max_processes; i++))
do 
    /path/to/myprog arg1 arg2 > /tmp/myprog.${i}.log &
done

Or if the output of each one is command is relevant during execution, you can setup screen.

vi .screenrc
screen -t inst1    1 /path/to/myprog arg1 arg2
screen -t inst2    2 /path/to/myprog arg1 arg2
screen -t inst3    3 /path/to/myprog arg1 arg2
screen -t inst4    4 /path/to/myprog arg1 arg2

The screen requires more manual work.

You can do something like:

max_processes=20
for ((i=0; i<$max_processes; i++))
do 
    /path/to/myprog arg1 arg2 > /tmp/myprog.${i}.log &
done

Or if the output of each command is relevant during execution, you can setup screen.

vi ~/.screenrc
screen -t inst1    1 /path/to/myprog arg1 arg2
screen -t inst2    2 /path/to/myprog arg1 arg2
screen -t inst3    3 /path/to/myprog arg1 arg2
screen -t inst4    4 /path/to/myprog arg1 arg2

The screen requires more manual work.