exit

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, exit status will be that of the most recent command. exit can be issued at the command line to close a window (log out).

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