=pod

=head1 SUMMARY

IPC::Locker provides a server for locks and a Perl package for clients to
access that server.  The result is that clients can access named locks on a
Internet wide basis, solving critical section problems without the mess of
NFS or other file locking techniques.

The latest version is available from CPAN and from
L<https://www.veripool.org/ipc-locker>.

=head1 EXAMPLE

   use IPC::Locker;
   # ...
   my $lock = IPC::Locker->lock(host=>'example.std.com');
   # ... Critical section ...
   $lock->unlock;

=head1 INSTALLATION

=head2 Build and Install the Package

=head3 Install from CPAN:

   cpan install IPC::Locker

=head3 Or, build from sources:

   # Obtain distribution kit
   git clone git@github.com:veripool/IPC-Locker.git
   # Build
   cd IPC-Locker
   git pull
   perl Makefile.PL
   make
   make test
   make install

=head2 Install the Daemons

You may wish to install C<lockerd> and C<pidstatd> in a init.rc file so
that it is run at system startup.  Depending on your distribution, you may
be able to just:

   cp init.d/lockerd   /etc/init.d/lockerd  # On one server only
   cp init.d/pidstatd  /etc/init.d/pidstatd  # On all machines

Edit paths in above to point to /usr/bin instead of /usr/local/bin, if needed.

   service lockerd start  # On one server only
   service pidstatd start  # On all machines
   chkconfig lockerd on  # On one server only
   chkconfig pidstatd on  # On all machines

If you get "This account is currently not available."  you need to change
the daemon account from a shell of /sbin/nologin to /sbin/bash.

=head2 Nagios

If you are using Nagios http://www.nagios.org, sample scripts to check the
daemons are included in the nagios subdirectory.

=head1 DOCUMENTATION

IPC::Locker provides the following programs/packages:

=head2 lockerd

C<lockerd> is the daemon that supports IPC::Locker. See C<man
lockerd> after installation.

=head2 IPC::PidStat

C<IPC::PidStat> is a Perl package which answers the question, "is pid X
running on host Y?".  See C<man IPC::PidStat> after installation.

=head2 pidstat

C<pidstat> is a program which answers the question, "is pid X running on
host Y?".  See C<man pidstat> after installation.

=head2 pidstatd

C<pidstat> is the daemon that supports C<IPC::PidStat> and C<pidstat>. See
C<man pidstatd> after installation.

=head2 pidwatch

C<pidwatch> is a program which starts other programs, and kill that program
when another job exists.  See C<man pidwatch> after installation.

=head2 uriexec

C<uriexec> is a simple wrapper which allows executing a command which is
quoted using URI escapes.  This prevents layered shells from interpreting
special characters.  See C<man uriexec> after installation.

=head2 check_lockerd and check_pidstatd

C<check_lockerd> and C<check_pidstatd> are Nagios plugins to check
C<lockerd> and C<pidstatd>.  See the Nagios documentation at
https://www.nagios.org for information on installing plugins.

=head1 LICENSE

This package is Copyright 1999-2019 by Wilson Snyder <wsnyder@wsnyder.org>.

This program is free software; you can redistribute it and/or modify it
under the terms of either the GNU Lesser General Public License Version 3
or the Perl Artistic License Version 2.0.  This code is provided with no
warranty of any kind, and is used entirely at your own risk.
