#!/bin/sh

# tac.sh

# 20050515 PixEye@bigfoot.com	Creation

# tac is the opposite of cat
# It displays lines of file in reverse order (starting from end to begin)

nbps=1				# Number of wanted parameters (without options)
cmd=`basename $0`		# Command name
usage="Usage: $cmd [-h]"	# Help message:
usage=$usage"\n\tDisplay this help message.\n"
usage=$usage"\nUsage: $cmd <filename> [...]"
usage=$usage"\n\t$cmd is the opposite of cat."
usage=$usage"\n\tIt displays lines of file in reverse order"
usage=$usage"\n\t (starting from end to begin)."

if test `uname` != "HP-UX" ; then e="-e" ; fi	# HP-UX echo case

if [ $# -ne $nbps -o "$1" = "-h" ] ; then	# Check parameters number
	echo $e $usage 1>&2 ; exit 2		# Display message help and exit
fi

tmp1="/tmp/$cmd.tmp"
tmp2="/tmp/$cmd""2.tmp"

while [ "$#" -ge 1 ]
do
	file="$1"
	if test ! -r "$file" ; then	# If the file in unreadable:
		echo $e "$cmd: \"$file\" cannot read that file!" 1>&2 ; exit 3
	fi

	> "$tmp1"
	while read line
	do
		echo "$line" > "$tmp2"
		cat "$tmp1" >> "$tmp2"
		mv "$tmp2" "$tmp1"
	done < "$file"

	cat "$tmp1"
	rm -f "$tmp1"

	shift
done

exit 0		# Normal exit

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