#!/bin/sh -u
#   $0   (no arguments)
# Test numeric arguments containing blanks.
#
# Most versions of the shell accept blanks in numeric arguments to test, 
# some versions do not.  Bash shells keep their version number in
# the variable $BASH_VERSION:
#
#   $ echo $BASH_VERSION
#   2.04.12(1)-release
#
# I've found that version 2 of the bash shell doesn't allow blanks.
# (Version 1 does!)
#
# If you use a shell that doesn't allow blanks:
#
#   Why do the first three tests generate error messages?
#   Why do the second three tests work correctly?
#
# This script uses conditional command execution via "&&".
# The command to the right of "&&" only executes if the command to the
# left of the "&&" exits with a zero (good) return status.
#
# Try running this script under "sh -x" to see the shell processing.
#
# -IAN! idallen@ncf.ca   June 2001

x="  123  "
y="  456  "

# If your shell doesn't like blanks, these three fail using "$x" and "$y":
#
if [ "$x" -lt "$y" ]; then
	echo "You never see this.  Why?"
fi
test "$x" -lt "$y" && echo "You never see this.  Why?"
[ "$x" -lt "$y" ] && echo "You never see this.  Why?"

# These three work in all shells using $x and $y:
#
if [ $x -lt $y ]; then
	echo "You do see this.  Why?"
fi
test $x -lt $y && echo "You do see this.  Why?"
[ $x -lt $y ] && echo "You do see this.  Why?"