in reply to Write to existing file with character insert
I'm struggling to work out how to successfully search and replace this string in the same file and save it off.
If you inserting or removing something from a file you have to rewrite all the file starting from the place where you're inserting or removing data. Therefore a practical approach is to read data from file, change it as needed, and save into a new file. Then rename new file to replace the original. You don't have to implement it yourself though, just use edit_file_lines function from the File::Slurp module.