You can't do what you are trying to do with the file...unless you write out exactly the same number of characters as were there before. Usually instead you open a new file, write out all the lines (whether changed or unchanged) to it, then rename it to replace the existing file. For a quick script operating on only small files, you could use Tie::File to automate most of this for you.
in reply to Re^4: trouble with regular expressions
in thread trouble with regular expressions
A math joke: r = | |csc(θ)|+|sec(θ)|-||csc(θ)|-|sec(θ)|| |