echo "$(uname) Bash version: $BASH_VERSION" # Parallelly executing programs
main()
{
    for (( i=0; i<=10; i++ ))
    do echo "$i $1"; done
}
(main "from process 1"; echo $$; sleep 5; exit 0; ) &
# ( ( main "from process 2"; echo $$; sleep 5;) ) &
(main "from process 2"; echo $$; sleep 5; ) &
wait

Darwin Bash version: 3.2.57(1)-release
0 from process 1
1 from process 1
2 from process 1
3 from process 1
4 from process 1
5 from process 1
6 from process 1
7 from process 1
8 from process 1
9 from process 1
10 from process 1
68096
0 from process 2
1 from process 2
2 from process 2
3 from process 2
4 from process 2
5 from process 2
6 from process 2
7 from process 2
8 from process 2
9 from process 2
10 from process 2
68096

Darwin Bash version: 5.0.3(1)-release
0 from process 1
1 from process 1
2 from process 1
3 from process 1
4 from process 1
5 from process 1
6 from process 1
7 from process 1
8 from process 1
9 from process 1
10 from process 1
68121
0 from process 2
1 from process 2
2 from process 2
3 from process 2
4 from process 2
5 from process 2
6 from process 2
7 from process 2
8 from process 2
9 from process 2
10 from process 2
68121