Unix in a Nutshell, 4th Edition

Name

exit

Synopsis

    exit [n]

Exit a shell script with status n (e.g., exit 1). n can be 0 (success) or nonzero (failure). If n is not given, the shell’s exit status is that of the most recent command. exit can be issued at the command line to close a window (log out). Exit statuses can range in value from 0 to 255.

Example

if [ $# -eq 0 ]
    then
       echo "Usage: $0 [-c] [-d] file(s)" 1>&2
       exit 1               # Error status
    fi