The suspend is a bash built in command. It is used to suspend the execution of this shell until it receives a SIGCONT signal. Unless forced, login shells cannot be suspended. This command is equivalent of pressing Ctrl+Z in your shell. See example below for more info.
The syntax is:
The -f option force the suspend, even if the shell is a login shell.
Type the following command to become a root user:
$ sudo -i
Now run command as root user:
# date # id
Suspend shell execution of 'sudo -i' command:
# suspend -f
You are now back to normal shell:
To move suspended (sudo -i) job to the foreground use fg: