How to delete a line from the file with php?

Question

I have a file named $dir and a string named $line, I know that this string is a complete line of that file but I don't know its line number and I want to remove it from file, what should I do?

Is it possible to use awk?

Answer 1

Read the lines one by one, and write all but the matching line to another file. Then replace the original file.