1. Perl in the Command Line

3. It will execute BEGIN , UNITCHECK , CHECK , and use blocks, because these are considered as occurring outside the execution of your program.

4. It will not execute INIT and END blocks.

6. -W: Enables all warnings regardless of no warnings or $^W .

7. -X: Disables all warnings regardless of use warnings or $^W .

8. $> perldoc perllexwarn

10. -d:DProf : executes the program using the Devel::DProf profiler, combined with dprofpp may help you to find where is your program slow.

11. $> perldoc perldebtut $> perldoc perldebug

14. $> perl –Mdiagnostics script.pl Get better error message.

15. perl -MLWP::Simple -e 'print get($ARGV[0]), "
"' http://perl.com Better as an alias.

20. or the simpler $> perl -pe ' s/PHP/Perl/g ' in.txt

21. It's very common to see command line programs that use Unix I/O redirection like this: $> perl -pe 's/PHP/Perl/g' in.txt > out.txt

23. -i[extension] : edit in place. Case extension exists the original file is renamed, otherwise the file is overwitten.

24. If the extension doesn't contain a * , then it is appended to the end of the current filename. If the extension does contain one or more * characters, then each * is replaced with the current filename.

26. It assigns $ to have the value of octnum . Without octnum, $ will be assigned to $/ .

28. Adds $ (the output record separator) to each print

30. -F: choses a diferent separator

31. perl -F, -ane 'print join " ", @F' data.csv converts a csv into a tsv. Not really true but enough for example propose.

33. Q&A