#!/bin/sh -u
#   $0 pathname
# Tells whether a pathname is a file or directory.
# Lists the contents of a directory; line counts a file.
#
# The syntax line, above, shows that this script expects one argument
# and that argument is suposed to be a pathname (not a number or a userid).
# The two lines that follow it give a quick synopsis of what the script does.
#
# 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    October 2001

# The PATH is necessary to make sure that the shell that executes
# this script can find all the commands used in the script.
# The umask sets the permissions on any files created.
# This is a standard Unix path.  It should work anywhere in the world,
# for standard Unix commands.  It does not include any X windows directories.
# The umask here is appropriate for general-purpose scripts.  It is not a
# secure umask (077) that might be used for sensitive processing.
#
export PATH=/bin:/usr/bin
umask 022

# Make sure we have exactly one argument to this script.
# Issue an error message explaining what was expected and showing the
# actual number of args found, followed by the text of those args.
# Error messages always go on standard error, never standard output.
#
if [ "$#" -ne 1 ]; then
	echo 1>&2 "$0: Expecting exactly one argument; found $# ($*)"
	exit 1
fi

# Test to see if the pathname is a directory.
# List the contents and then exit, if it is.
# Check the error code on the ls command.
#
if [ -d "$1" ]; then
	echo "'$1' is a directory; here is the content:"
	ls "$1" || exit $?
	exit 0
fi

# Test to see if the pathname is a file.
# Get a line count of lines and then exit, if it is.
# Check the error code on the wc command.
# By redirecting input from wc instead of using a command-line argument,
# wc does not produce a file name in its output.  That looks better.
#
if [ -f "$1" ]; then
	echo "'$1' is a file; here is a count of the lines:"
	lines=$(wc -l <"$1") || exit $?
	echo "It contains $lines lines"
	exit 0
fi

# The command line argument is not a file or directory - print an error
# message.  Exit with some non-zero return status.  (3 is arbitrary.)
# Error messages always go on standard error, never standard output.
#
echo 1>&2 "$0: '$1' is not an existing file or directory"

exit 3  # exit with some non-zero return status to indicate failure