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NAME

Debug::Fork::Tmux - Makes fork() in debugger to open a new Tmux window

VERSION

This documentation refers to the module contained in the distribution Debug-Fork-Tmux version 1.000012.

SYNOPSIS

#!/usr/bin/perl -d
#
# ABSTRACT: Debug the fork()-contained code in this file
#
## Works only under Tmux: http://tmux.sf.net
#
# Make fork()s debuggable with Tmux
use Debug::Fork::Tmux;

# See what happens in your debugger then...
fork;

DESCRIPTION

Make sure you have the running Tmux window manager:

$ tmux
  • Only Tmux version 1.6 and higher works with Debug::Fork::Tmux. See "DEPENDENCIES".
  • It is not necessary to run this under Tmux, see ["Attaching to the other Tmux session"](#Attaching to the other Tmux session).

Then the real usage example of this module is:

$ perl -MDebug::Fork::Tmux -d your_script.pl

As Perl's standard debugger requires additional code to be written and used when the debugged Perl program use the fork() built-in.

This module is about to solve the trouble which is used to be observed like this:

######### Forked, but do not know how to create a new TTY. #########
Since two debuggers fight for the same TTY, input is severely entangled.

I know how to switch the output to a different window in xterms, OS/2
consoles, and Mac OS X Terminal.app only.  For a manual switch, put the
name of the created TTY in $DB::fork_TTY, or define a function
DB::get_fork_TTY() returning this.

On UNIX-like systems one can get the name of a TTY for the given window
by typing tty, and disconnect the shell from TTY by sleep 1000000.

All of that is about getting the pseudo-terminal device for another part of user interface. This is probably why only the GUIs are mentioned here: OS/2 'Command Prompt', Mac OS X's Terminal.app and an xterm. For those of you who develop server-side stuff it should be known that keeping GUI on the server is far from always to be available as an option no matter if it's a production or a development environment.

The most ridiculous for every TUI (the ssh particularly) user is that the pseudo-terminal device isn't that much about GUIs by its nature so the problem behind the bars of the perl5db.pl report (see more detailed problem description at the PerlMonks thread) is the consoles management. It's a kind of a tricky, for example, to start the next ssh session initiated from the machine serving as an sshd server for the existing session.

Thus we kind of have to give a chance to the consoles management with a software capable to run on a server machine without as much dependencies as an xterm. This module is a try to pick the Tmux windows manager for such a task.

Because of highly-developed scripting capabilities of Tmux any user can supply the 'window' or a 'pane' to Perl's debugger making it suitable to debug the separate process in a different UI instance. Also this adds the features like groupware: imagine that your mate can debug the process you've just fork()ed by mean of attaching the same tmux you are running on a server. While you keep working on a process that called a fork().

SUBROUTINES/METHODS

All of the following are functions:

PUBLIC

DB::get_fork_TTY()

Finds new TTY for the fork()ed process.

Takes no arguments. Returns Str name of the tty device of the 's new window created for the debugger's new process.

Sets the $DB::fork_TTY to the same Str value.

PRIVATE

_spawn_tty()

Creates a TTY device and returns Str its name.

_tmux_new_window()

Creates a given tmux window and returns Str its id/number.

_tmux_window_tty( $window_id )

Finds a given tmux window's tty name and returns its Str name based on a given window id/number typically from "_tmux_new_window()".

_read_from_cmd( $cmd => @args )

Takes the list containing the Str system() command and Array its arguments and executes it. Reads Str the output and returns it. Throws if no output or if the command failed.

_croak_on_cmd( $cmd => @args, $happen )

Takes the Str command, Array its arguments and Str the reason of its failure, examines the $? and dies with explanation on the system() command failure.

CONFIGURATION AND ENVIRONMENT

The module requires the Tmux window manager for the console to be present in the system.

This means that it requires the Unix-like operating system not only to have a fork implemented and a TTY device name supplement but the system should have Tmux up and running.

Therefore Cygwin for example isn't in at this moment, see the explanation why.

Configuration is made via environment variables, the default is taken for each of them with no such variable is set in the environment:

DFTMUX_FQFN

The tmux binary name with the full path.

Default : The first of those for executable to exist:

  • PATH environment variable contents
  • Path to the Perl binary interpreter
  • Current directory

and just the tmux as a fallback if none of above is the location of the tmux executable file.

DFTMUX_CMD_NEWW

The system() arguments for a tmux command for opening a new window and with output of a window address from tmux. String is sliced by spaces to be a list of parameters.

Default : neww -P

DFTMUX_CMD_NEWW_EXEC

The system() or a shell command to be given to the DFTMUX_CMD_NEWW command to be executed in a brand new created window. It should wait unexpectedly and do nothing till the debugger catches the device and puts in into the proper use.

Default : sleep 1000000

DFTMUX_CMD_TTY

Command- line parameter(s) for a tmux command to find a tty name in the output. The string is sliced then by spaces. The tmux's window address is added then as the very last argument.

Default : lsp -F #{pane_tty} -t

Earlier versions' SPUNGE_* environment variables

Till v1.000009 the module was controlled by the environment variables like SPUNGE_TMUX_FQDN. Those are deprecated and should be replaced in your configuration(s) onto the DFTMUX_-prefixed ones.

Attaching to the other Tmux session

For the case you can not or don't want to use the current tmux session you are running in, you may want to have the separate tmux server up and running and use its windows or panes to be created. This can be done by mean of prepending the correct -L or -S switch to the start of the every of the command-line parameters string to be used, for example:

$ DFTMUX_CMD_NEWW="-L default neww -P" \
> DFTMUX_CMD_TTY="-L default lsp -F #{pane_tty} -t" \
> perl -MDebug::Fork::Tmux -d your_script.pl

DIAGNOSTICS

  • The command ...

    Typically the error message starts with the command the Debug::Fork::Tmux tried to execute, including the command's arguments.

  • failed opening command: ...

    The command was not taken by the system as an executable binary file.

  • ... didn't write a line

  • failed reading command: ...

    Command did not output exactly one line of the text.

  • ... did not finish

    Command outputs more than one line of the text.

  • provided empty string

    Command outputs exactly one line of the text and the line is empty.

  • failed to execute: ...

    There was failure executing the command

  • child died with(out) signal X, Y coredump

    Command was killed by the signal X and the coredump is (not) located in Y.

  • child exited with value X

    Command was not failed but there are reasons to throw an error like the wrong command's output.

DEPENDENCIES

* Perl 5.8.9+ is available from The Perl website

* Config, Cwd, DB, ExtUtils::MakeMaker, File::Find, File::Spec, File::Basename, Scalar::Util, Test::More are available in core Perl distribution version 5.8.9 and later

* Const::Fast is available from CPAN

* Module::Build is available in core Perl distribution since version 5.9.4

* Sort::Versions is available from CPAN

* Test::Exception is available from CPAN

* Test::Most is available from CPAN

* Test::Strict is available from CPAN

* Env::Path is available from CPAN

* autodie is available in core Perl distribution since version 5.10.1

* Tmux v1.6+ is available from The Tmux website

Most of them can easily be found in your operating system distribution/repository.

BUGS AND LIMITATIONS

You can make new bug reports, and view existing ones, through the web interface at http://bugs.vereshagin.org/product/Debug-Fork-Tmux.

WEB SITE

The web site of Debug::Fork::Tmux currently consists of only one page cause it's a very small module.

You may want to visit a GitHub page, too.

SUPPORT

Perldoc

You can find documentation for this module with the perldoc command.

perldoc Debug::Fork::Tmux

Websites

The following websites have more information about this module, and may be of help to you. As always, in addition to those websites please use your favorite search engine to discover more resources.

Email

You can email the author of this module at peter@vereshagin.org asking for help with any problems you have.

Bugs / Feature Requests

Please report any bugs or feature requests by email to peter@vereshagin.org, or through the web interface at http://bugs.vereshagin.org/product/Debug-Fork-Tmux. You will be automatically notified of any progress on the request by the system.

Source Code

The code is open to the world, and available for you to hack on. Please feel free to browse it and play with it, or whatever. If you want to contribute patches, please send me a diff or prod me to pull from your repository :)

http://gitweb.vereshagin.org/Debug-Fork-Tmux

git clone https://github.com/petr999/Debug-Fork-Tmux.git

AUTHOR

Peter Vereshagin peter@vereshagin.org

COPYRIGHT AND LICENSE

This software is Copyright (c) 2013 by Peter Vereshagin.

This is free software, licensed under:

The (three-clause) BSD License

SEE ALSO

Please see those modules/websites for more information related to this module.

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

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Makes fork() in debugger to open a new Tmux window

gitweb.vereshagin.org/Debug-Fork-Tmux/README.html

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