exit

type -a exit

exit is a shell builtin

exit --help

exit: exit [n]
    Exit the shell.

    Exits the shell with a status of N.  If N is omitted, the exit status
    is that of the last command executed.

#!/bin/bash

FIRE_DIRECTORY="${1}"

if [ -d "${FIRE_DIRECTORY}" ]; then
        rmdir "${FIRE_DIRECTORY}"
        echo "Successfully extinguished the fire in '${FIRE_DIRECTORY}'!"
        exit 0;
else
        echo "Failed to extinguish fire in '${FIRE_DIRECTORY}': Fire not found."
        exit 1;
fi

mkdir apartment-1234
./extinguish-fire.sh apartment-1234
echo $?

0

./extinguish-fire.sh apartment-1234
echo $?

1

sh -c 'exit 0'
if [ $? -eq 0 ]; then
	echo "Success! The shell script ran successfully!"
else
	echo "The script failed... Try re-running it I guess?"
fi

Success! The shell script ran successfully!

sh -c 'exit 1'
if [ $? -eq 0 ]; then
	echo "Success! The shell script ran successfully!"
else
	echo "The script failed... Try re-running it I guess?"
fi

The script failed... Try re-running it I guess?

# Opening GNU screen first to increase the shell level:
screen

#  Check current shell level:
echo $SHLVL

2

#  Exit from screen:
exit

#  Check current shell level again:
echo $SHLVL

1

exit  #  Exit command will now close the terminal window