#!/bin/sh -u
#
#     $0  string
#
# A script that chooses cases based on the first cmd line argument.
#
# WARNING: Many of the comments in this file are "Instructor-Type"
#   comments and are *not* appropriate for real scripts.  Do not put
#   "Instructor-Type" comments into the scripts that you submit for marking.
#   I put them in my example files because I am teaching you how to
#   write scripts; do not submit my teaching comments back to me again.
#   Read the week7.txt notes for more details on good comment style.
#
# -IAN! idallen@ncf.ca  June 2001

# All scripts must start with lines similar to these two:
#
export PATH=/bin:/usr/bin
umask 022

# The first thing all programs must do is validate their arguments.
#
# This case statement could be an "if" statement.
# Note how we do nothing (no command given) if there is one argument.
#
case "$#" in
1) ;;
*) echo 1>&2 "$0: Expecting exactly one argument; found $#"
   exit 1
   ;;
esac

# Sometimes, echoing the input is a good idea.
# Demonstration scripts often do this; real scripts do it less often.
#
echo "The command line argument was '$1'."

# Choose cases based on pattern matching the input.
# Remember!  First match wins - only one of these cases will execute.
#
# Since we validated the existence of a command line argument, we know
# that $1 has a value (though it could be an empty string).
#
# Style: If the pattern of the case fits before the first tab stop,
#        you can put the rest of the case (the commands) on the same
#        line after a tab.  If it doesn't, start the commands on a new
#        line, indented one tab stop.
#
case "$1" in
"")	echo "Your input is empty (no characters)." ;;
*" "*)	echo "Your input contains blanks." ;;
[0-9][0-9]*)
	# The pattern in this case is wider than one tab stop,
	# so I put the command on a new line for readability.
	echo "Your input starts with two digits."
	;;
[0-9]*)	echo "Your input starts with only one digit." ;;
*[0-9])	echo "Your input ends with a digit." ;;
.*)	echo "Your input starts with a dot." ;;
?|??|???|????)
	# The pattern in this case is wider than one tab stop,
	# so I put the commands on a new line for readability.
	# Use tr to delete the newline normally added by "echo".
	# Check the return code of the wc in case of error.
	#
	echo "Your input is between one and four characters long."
	width=$(echo "$1" | tr -d '\n' | wc -c) || exit $?
	echo "In fact, it is exactly $width characters long."
	;;
*)	echo "*: (DEFAULT) You typed '$1'."
	echo "This is the default case."
	echo "The * pattern always matches."
	;;
esac

exit 0