How can I debug a Perl script

Question

When I run a Perl script  how can I debug it  For example  in ksh I add the -x flag  But how I do the same in Perl

User · Answer

perl -d your script pl args   is how you debug Perl  It launches you into an interactive gdb-style command line debugger

User · Answer

If using an interactive debugger is OK for you  you can try perldebug

User · Answer

If you want to do remote debugging  for CGI or if you don t want to mess output with debug command line   use this   Given test   use v5 14  say 1  say 2  say 3    Start a listener on whatever host and port on terminal 1  here localhost 12345      nc -v -l localhost -p 12345   For readline support use rlwrap  you can use on perl -d too      rlwrap nc -v -l localhost -p 12345   And start the test on another terminal  say terminal 2      PERLDB OPTS  RemotePort localhost 12345  perl -d test   Input Output on terminal 1   Connection from 127 0 0 1 42994  Loading DB routines from perl5db pl version 1 49 Editor support available   Enter h or  h h  for help  or  man perldebug  for more help   main   test 2      say 1    DB lt 1 gt  n main   test 3      say 2    DB lt 1 gt  select  DB  OUT    DB lt 2 gt  n 2 main   test 4      say 3    DB lt 2 gt  n 3 Debugged program terminated   Use q to quit or R to restart  use o inhibit exit to avoid stopping after program termination  h q  h R or h o to get additional info    DB lt 2 gt    Output on terminal 2   1   Note the sentence if you want output on debug terminal  select  DB  OUT   If you are Vim user  install this plugin  dbg vim which provides basic support for Perl

User · Answer

I would also recommend using the Perl debugger   However  since you asked about something like shell s -x have a look at the Devel  Trace module which does something similar

User · Answer

To run your script under the Perl debugger you should use the -d switch   perl -d script pl   But Perl is flexible  It supplies some hooks  and you may force the debugger to work as you want  So to use different debuggers you may do   perl -d DebugHooks  Terminal script pl   OR perl -d Trepan script pl   Look these modules here and here   There are several most interesting Perl modules that hook into Perl debugger internals  Devel  NYTProf and Devel  Cover  And many others

User · Answer

The most effective debugging tool is still careful thought  coupled   with judiciously placed print statements       Brian Kernighan   Unix for Beginners   1979     And enhancing print statements with Data  Dumper

User · Answer

Use Eclipse with EPIC  It gives you a nice IDE with debugging possibilities  including the ability to place breakpoints and the Perl Expression View for inspecting the value of variables

User · Answer

Note that the Perldebugger can also be invoked from the scripts shebang line  which is how I mostly use the -x flag you refer to  to debug shell scripts      usr bin perl -d

[perl] How can I debug a Perl script?

Examples related to perl

Examples related to debugging