#!/bin/bash

# This is a version of the script you are to write in 
# Exercise 1 of Module 4.
#
# Comments with numbers in square brackets, e.g. [1],
# begin sections of the script with the number indicating
# roughly the order in which you were asked to write
# that section.
#
#                            David Harrison - May 2002

# [4], [5]

# The name of the program.

PROGNAME=`basename $0`

# [8]

# This is the command to be executed. May be modified
# below.

LS='/bin/ls'

# [9], [10], [11]

# Process optional -l or -m flag

case $1 in                # We could set, for example:
	-l) LS="$LS -l"   #    LS='/bin/ls -l'
		shift;;   # and similarly for the -m flag
	-m) LS="$LS -m"   # but this way I only specify the
		shift;;   # location of /bin/ls in one place.
esac                      # This is good coding practice.

# [1]

# If no arguments, just execute $LS and exit.

if [ $# -eq 0 ]
then
	$LS
	exit
fi

# [2]

# We have arguments. Assemble them into $FILENAMES

FILENAMES=''

while [ $# -gt 0 ]
do

	# [3], [6]

	# If no such file, issue a message and exit
	# with $? = 1

	if [ ! -f $1 ]
	then

		# [7]

		# Direct echo's output to stderr.
		echo "$PROGNAME: $1: No such file found" 1>&2
		exit 1
	fi

	FILENAMES="$FILENAMES $1"
	shift

done

$LS $FILENAMES