Shell Programming and Scripting

@arr=(This,THis,THIS);
$n=0;
opendir(DIRECTORY, '.') or die "Can't open current directory.";
@files=readdir(DIRECTORY);
closedir DIRECTORY;
for($i=2;$i<$#files;$i++){
print "Begin change file:",$files[$i],"\n";
open FH,"<$files[$i]";
while(<FH>){
if($arr[$n]){
$_=~s/this/$arr[$n]/;
}
print $_;
}
close(FH);
print "End change file:",$files[$i],"\n\n";
$n++;
}

n=0
for i in *
do
        temp=""
        n=`expr $n + 1`
        temp=`cat ../replace | head -"$n" |tail -1`
        cat $i | nawk -v t="$temp" '{
                gsub(/this/,t,$0)
                print $0
        }'
done

n=0
for i in *
do
        temp=""
        n=`expr $n + 1`
        temp=`sed -n "${n}p" ../replace`
        nawk -v t="$temp" '{
                gsub(/this/,t,$0)
                print $0
        }' "$i" >tmp
       # Don't replace file if no change
       cmp "$i" tmp >/dev/null && continue
       mv "$i" "$i"~
       mv tmp "$i"
done
rm -f tmp