bash parallelism example

go

#! /usr/bin/env bash
bg_process()
{
  sleep 1
  for i in a b c d e f g h i j k l m n o p
  do
    echo $i
    sleep 1
  done
}

rm -f log
rm -f pid

( bg_process & echo $! > pid ) | tee log &

until [ -f log ]
do
     sleep 0.5
done

( tail -f -n0 log & ) | grep -q h 1> /dev/null
echo booya
( tail -f -n0 log & ) | grep -q m 1> /dev/null
kill -9 $(cat pid)

output

❯ ./go
a
b
c
d
e
f
g
h
booya
i
j
k
l
m