How to run shell commands sequentially or at the same time entered on a single line.
echo 1 sleep 5s echo 2
(A) run several commands using the control operator ";" (semicolon) which will execute them sequentially. The shell will wait for each command to terminate in turn. The return status is the exit status of the last command executed.
echo 1; sleep 5s; echo 2
(B) run several commands using the control operator "&" (ampersand)
echo 1 & sleep 5s & echo 2
(C) run several commands using double ampersands
echo 1 && sleep 5s && echo 2