What does Perl's -p command-line switch do?

Question

perl -p -i.bak -e 's/search_str/replace_str/g' filename

What do -p, -i.bak s/ and /g mean?

Answer 1

• -p: assume 'while (<>) { ... }' loop around program and print each processed line too.
• -i.bak: change the input file (filename) inplace and create the file filename.bak as backup.
• s in s/: to mark substitution
• g - make the substitution globally..that is don't stop after first replacement.