How can I prepend a string to the beginning of each line in a file?

Question

I have the following bash code which loops through a text file, line by line .. im trying to prefix the work \'prefix\' to each line but instead am getting this error:

Answer 1

A Perl way to do it would be:

perl -p -e's/^/prefix' filename

or

perl -p -e'$_ = "prefix $_"' filename

In either case, that reads from filename and prints the prefixed lines to STDOUT.

If you add a -i flag, then Perl will modify the file in place. You can also specify multiple filenames and Perl will magically do all of them.