I'm new to mojolicious but have been using Perl for some time. I have to jump through some hoops but I can get the interactive Perl debugger (and Komodo) working with remote connections for Apache but I can't find anything about interactive debugging with hypnotoad or morbo.
The command line examples in the basic tutorial on http://mojolicio.us/perldoc/Mojolicious/Guides/Tutorial#Hello-World work fine because you can launch them with perl -d, but I don't see anyway to tell the hypnotoadctl script to put the service in interactive debug mode ala apache.
Is this not possible? Hints? Tips? Pointers?
morbo and hypnotoad are perl programs, so you can launch them with the -d switch.
perl -d $(which morbo) myMojoApp.pl
It's probably easiest to sprinkle a bunch of $DB::single = 1 statements around you app where you want your initial breakpoints to go and run c as the first debugger command. When you run a request that hits a breakpoint, you'll get a debugger prompt in the terminal that launched morbo.
hypnotoad will be trickier to use with the debugger because it quickly closes all the standard filehandles, calls fork several times, and becomes a daemon.
As JHThorsen points out, standard Mojolicious tests are actually ordinary Perl scripts, so you can debug your tests with:
perl -d t/mytest.t
The -Ilib adds the lib/ directory to the #INC include list so your modules will be loaded.
One catch is that many modules are not loaded until execution time, so if the debugger hassles you about symbols that aren't loaded yet, you'll probably want to set breakpoints after forcing a debug prompt with a carefully inserted
$DB::single = 1;
Thanks to 'pink_mist'. You can do:
perl -d myMojoApp.pl daemon -l http://*:29849
But application config is not applyied. I do not know why.
Related
Say my debugger stops at a breakpoint. Is there any way to run/send arbitrary Perl code to the debugger?
For example, say I stop the debugger at a location with the statement:
$DB::single = 1
I would like to be able to:
Type and execute general Perl statements from the debugger prompt
Run scripts
Anything you type in the debugger that isn't recognized as a debugger command is interpreted as perl and run. You can run a file using require or do, although I'm not sure what you have in mind when you say "interactively" run code from another file.
I have a Perl program written by someone else. When I run it, it silently exits without writing anything to the logfile. Is there a way I can run this Perl program step by step, line by line by the interpreter and thus get to see where it terminates?
Yes, there is the Perl debugger which you can invoke with perl -d.
Documentation can be found in perldoc perldebug and perldoc perldebtut.
Probably the most useful commands would be:
s - step into current line.
n - step over current line.
r - step out of current function.
p <expr> - print the expression.
b <line|subnm> - sets a breakpoint
T - produce a stack trace.
c [<line|subnm>] - continue running with optional one-time breakpoint.
h - help (for other commands).
Hachi has the answer. Use the Perl debugger by running perl with the -d flag. For information on how to use the debugger past starting it, see the Perl Debugging Tutorial.
There is a Perl module called "ptkdb" which is a standalone Perl interactive debugger. It works using the Tcl/Tk GUI, so you'll need that, too.
Depending on your OS you'll need to add some required modules.
Invoke it using
perl -d:ptkdb <your script>
If running some Unix/Linux system, you also need an X server.
There are two ways. The first is the one which Hachi and llioin already gave which is using the command-line switch "-d".
Or use an IDE. I am tried and used Komodo IDE which works like charm.
Seems most are using the traditional way of print for debugging purpose, is there anyone that uses remote debug for perl in linux?
There are reasonably straightforward directions here: http://search.cpan.org/dist/Enbugger/lib/Enbugger.pod#From_gdb
Though that presupposes you have a long-running perl process (mod_perl, fastcgi, etc) that wasn't expecting to be run under the debugger. If you are just using vanilla CGI, you can configure your webserver to run perl -d and set the debugger to remote debugging via its TTY or RemotePort options. Or go ahead and use Enbugger in your actual perl code as in the directions above (again, setting TTY or RemotePort).
What sort of debugging? An actual perl debugger or using warn() with tail -f /var/log/apache/error.log?
In the end i would suggest swicting to Log::Log4perl. Unless you need an actual step by step debugger.
You you need an actual debugger, you likely won't want to use Apache in the mix. You can run your cgi from the command line and pass arguments CGI.pm.
I have this command that I load (example.sh) works well in the unix command line.
However, if I execute it in Perl using the system or ` syntax, it doesn't work.
I am guessing certain settings like environment variables and other external sh files weren't loaded.
Is there an example coding to ensure it will work?
More Updates on coding execution failure (I have been trying with different codes):
push (#JOBSTORUN, "cd $a/$b/$c/$d; loadproject cats; sleep 60;");
...
my $pm = new Parallel::ForkManager(3);
foreach my $job (#JOBSTORUN) {
$pm->start and next;
print(`$job`);
$pm->finish;
}
print "\n\n[DONE] FINISHED EXECUTING JOBS\n";
Output Messages:
sh: loadproject: command not found
Can you show us what you have tried so far? How are you running this program?
My first suspicion wouldn't be the environment if you are running it from a login shell. any Perl script you start (well, any program, really) inherits the same environment. However, if you are running the program through cron, then that's a different story.
The other mistakes I usually make in these situations is specifying the relative paths incorrectly. The paths are fine from the command line, but my Perl script has some other current working directory.
For general advice, see Interact with the system when Perl isn't enough. There's also a chapter in Learning Perl about this.
That's about the best advice you can hope for given the very limited information you've shared with us.
First time perl user and I am trying to debug some script to follow project logic and of course syntax.
Using cygwin after entering at command line $
$ perl -d sample.pl
Loading DB routines from perl5db.pl version 1.3
Editor support available.
Enter h or `h h' for help, or `perldoc perldebug' for more help.
main::(sample.pl:5): print 'Hello world.'; # Print a message
DB<1>
It hangs at the DB<1> line. I cannot enter anything at the prompt.
Is there a reason why this post is inappropriate? or how is this not clear?
This is the actual program code:
#!/usr/local/bin/perl
#
# Program to do the obvious
#
print 'Hello world.'; # Print a message
I upgraded my cygwin installation at home and ran into a similar problem (though maybe not the exact same problem -- the perl debugger still responds to my input but does not display my input, and fubars my input even after I quit the debugger). In the meantime while I figure what is going on, my workaround is to fire up xemacs, launch a shell (M-x shell), and run the perl debugger from the emacs buffer.
If this works for you, then there is something funky going on with your cygwin terminal settings. If your debugger hangs even in an emacs buffer, then something else funky is going on but I have no idea what it could be.
Sorry for reviving this three-year-old question, but I believe to have been hit with the same problem, and to have found the solution.
In my case, perl -de0 invokes infocmp from ncurses, which hangs in a weird way (can't kill it). And infocmp seemed to be a victim of my Avast anti-virus which is listed under BLODA as affecting Cygwin. Disabling it resolved the issue -- see if you have any of the listed applications and try disabling it (perhaps also try safe mode).
Also, simply renaming infocmp.exe allowed perl -d to run normally. In the end I used this approach and left my Avast running.
It could also be a different executable that perl -d is starting -- try to run whatever hangs with strace, see what is the last executable mentioned and try to see if that is the culprit.