#!/bin/sh -u
#
#     $0 filename
#
# idallen@ncf.ca
#
# A script that sorts its first argument (a file name).
# If the sort fails, print an error message.
# The output goes to the standard output; no redirection.
#
# Enhance the script to make sure that only one (exactly one)
# argument is supplied.  Print a message if not true.
#
# Enhance the script to make sure that the argument is not a
# directory.  Print a message if not true.

if test "$#" -ne 1 ; then
	echo "I want one argument.  You gave me $#."
	exit 1
fi

if test -d "$1" ; then
	echo "I want a file.  You gave me a directory named '$1'."
	exit 1
fi

if sort "$1" ; then
	:
else
	echo "The sort of '$1' didn't work: status $?"
fi

# Another, longer way to do the above test.  (Same output.)
#
# sort "$1"
# if test $? -eq 0 ; then
# 	:
# else
#	echo "The sort of '$1' didn't work: status $?"
# fi

# The shortest way to do the above test.  (Same output.)
# This uses the shell's "!" return code negation operator
# in front of the command to be run.
#
# if ! sort "$1" ; then
#	echo "The sort of '$1' didn't work: status $?"
# fi