echo 1. assignment with command substitution
time S1=`seq 1 50000`
time S2=`seq 1 50000 | grep 1794`
echo

echo 2. execution
time seq 1 50000 > /dev/null
time seq 1 50000 | grep 1794 > /dev/null
echo

echo 3. null builtin with command substitution
time : "`seq 1 50000`"
time : "`seq 1 50000 | grep 1794`"
echo

echo 4. null builtin with word splitting from variable
time : $S1
time : $S2
echo

echo 5. null builtin with command substitution and word splitting
time : `seq 1 50000`
time : `seq 1 50000 | grep 1794`
echo

echo 6. compgen with variable
time compgen -W "$S1" 1794 >/dev/null
time compgen -W "$S2" >/dev/null
echo

echo 7. compgen with command substitution
time compgen -W "`seq 1 50000`" 1794 >/dev/null
time compgen -W "`seq 1 50000 | grep 1794`" >/dev/null
echo

echo 8. compgen with variable, null match
time compgen -W "$S1" >/dev/null
echo

echo 9. compgen with command substitution, null match
time compgen -W "`seq 1 50000`" >/dev/null