How can I record changes made during in-place editing in Perl?

Question

I've scripted up a simple ksh that calls a Perl program to find and replace in files. The passed-in arg is the home directory:

 perl -pi -e 's/find/replace/g' $1/*.html

It works great. However, I'd like to output all the changes to a log file. I've tried piping and redirecting and haven't been able to get it work. Any ideas?

Thanks, Glenn

Answer 1

Something like this to send all changes to STDERR:

perl -pi -e '$old = $_; s/find/replace/g and warn "${ARGV}[$.]: $old $_"; close ARGV if eof' $1/*.html

Updated: Fixed $. on multiple files.

Answer 2

You can print to STDERR and redirect just the STDERR output to a file as below:

perl -pi -e 'chomp($prev=$_);s/find/replace/g and print STDERR "$ARGV - $.: $prev -> $_"; close ARGV if eof' $1/*.html 2> logfile.txt

edit: added the filename, and fixed line number display when multiple input files are used