#!/bin/sh -u
#  $0 pathname
# Read a text string and look for it in the argument pathname.
# Find lines that don't contain the string and put them in a file.
# -IAN!  idallen@ncf.ca

export PATH=/bin:/usr/bin
umask 022

# Must have one argument (a file name).
#
if [ $# -ne 1 ]; then
	echo 1>&2 "$0: Expecting 1 argument; found $# ($*)"
	exit 1
fi

# Make sure it is a file and is readable.
#
if [ ! -f "$1" ]; then
	echo 1>&2 "$0: '$1' is not a file"
	exit 1
fi
if [ ! -r "$1" ]; then
	echo 1>&2 "$0: '$1' is not a readable file"
	exit 1
fi

# Make sure the last line has the expected text.
#
last=$(tail -1 "$1")
if [ "$last" != "END OF FILE" ]; then
	echo 1>&2 "$0: Last line of '$1' is not correct."
	echo 1>&2 "$0: Last line is: $last"
	exit 1
fi

# Count and display the lines in the file.
#
count=$(wc -l <"$1")
echo "File '$1' contains $count lines."

# Prompt for (on stderr), read, and echo (on stdout) a text string.
#
echo 1>&2 "Please enter a text string:"
read str
echo "You entered '$str'."

# Count the lines containing the text string.
# Could also use "grep -c".
#
grepcount=$(grep "$str" "$1" | wc -l)
echo "String '$str' appears on $grepcount lines."

# If the text string doesn't appear on every line, save
# the lines that don't contain it in another file.
# Change the permissions on the file, and then rename it.
#
if [ "$grepcount" -lt "$count" ]; then
	f="no_string_found$$.txt"
	grep -v "$str" "$1" >"$f"
	chmod go-rwx "$f"
	ls -l "$f"
	mv "$f" unfound.txt
fi