Changeset 12580

Timestamp:

Mar 23, 2007, 2:40:11 PM (19 years ago)

Author:

jhoblitt

Message:

add nebdiskd support for an rcfile and daemonizing

Location:

trunk

Files:

• Nebulous-Server/Build.PL (modified) (1 diff)
• Nebulous-Server/bin/nebdiskd (modified) (3 diffs)
• Nebulous/Build.PL (modified) (1 diff)
• Nebulous/bin/nebdiskd (modified) (3 diffs)

trunk/Nebulous-Server/Build.PL

@@ -78 +78 @@
     create_makefile_pl  => 'passthrough',
     requires            => {
+        'Config::YAML'          => '1.42',
         'URI'                   => '1.30',
         'SOAP::Lite'            => '0.69',

trunk/Nebulous-Server/bin/nebdiskd

@@ -3 +3 @@
 # Copyright (C) 2007  Joshua Hoblitt
 # 
-# $Id: nebdiskd,v 1.1 2007-02-23 01:10:57 jhoblitt Exp $
+# $Id: nebdiskd,v 1.2 2007-03-24 00:40:11 jhoblitt Exp $
 
 use strict;
@@ -11 +11 @@
 $VERSION = '0.02';
 
-use Net::Server::Daemonize qw(daemonize);
+use Config::YAML;
+use DBI;
+use File::Spec;
+use Nebulous::Server::SQL;
+use Net::Server::Daemonize qw( daemonize unlink_pid_file );
 use Sys::Statistics::Linux::DiskUsage;
-use DBI;
-use Nebulous::Server::SQL;
 
 use Getopt::Long qw( GetOptions :config auto_help auto_version );
 use Pod::Usage qw( pod2usage );
 
-my ($debug, $db, $dbuser, $dbpass);
-
-$db     = $ENV{'NEB_DB'} unless $db;
-$dbuser = $ENV{'NEB_USER'} unless $dbuser;
-$dbpass = $ENV{'NEB_PASS'} unless $dbpass;
-
-our $POLL_INTERVAL = 5;
-
+my ($debug, $db, $dbuser, $dbpass, $pidfile, $stop, $restart, $verbose);
 GetOptions(
-    'debug|d'   => \$debug,
-    'db=s'      => \$db,
-    'user=s'    => \$dbuser,
-    'pass=s'    => \$dbpass,
+    'debug'     => \$debug,
+    'db|d=s'    => \$db,
+    'user|u=s'  => \$dbuser,
+    'pass|p=s'  => \$dbpass,
+    'pidfile=s' => \$pidfile,
+    'stop|s'    => \$stop,
+    'restart|r' => \$restart,
+    'verbose|v' => \$verbose,
 ) || pod2usage( 2 );
+
+my $rcfile = "$ENV{HOME}/.nebdiskrc";
+$rcfile = File::Spec->canonpath($rcfile);
+
+my $c = read_rcfile($rcfile);
+
+$db     ||= $c->get_db      || $ENV{'NEB_DB'};
+$dbuser ||= $c->get_dbuser  || $ENV{'NEB_USER'};
+$dbpass ||= $c->get_dbpass  || $ENV{'NEB_PASS'};
+$pidfile ||= $c->get_pidfile || "/var/tmp/nebdiskd";
+my $mounts = $c->get_mounts;
+my $poll_interval = $c->get_poll_interval || 5;
+
+if ($restart || $stop) {
+    my $status = kill_pid_file($pidfile);
+    exit($status) if $stop;
+}
+
+$c->set_db($db);
+$c->set_dbuser($dbuser);
+$c->set_dbpass($dbpass);
+$c->set_pidfile($pidfile);
+$c->set_poll_interval($poll_interval);
+$c->write;
 
 pod2usage( -msg => "Unknown option: @ARGV", -exitval => 2 ) if @ARGV;
@@ -39 +62 @@
 
 daemonize(
-    'jhoblitt', # User
-    'wheel',    # Group
-    undef       # PID file
+    $<,     # User
+    $),     # Group
+    $pidfile,  # PID file
 ) unless $debug;
 
-my $sql = Nebulous::Server::SQL->new;
-
-my $dbh = DBI->connect(
-    "DBI:mysql:database=$db:host=localhost",
-    $dbuser,
-    $dbpass,
-    {
-        RaiseError => 1,
-        PrintError => 0,
-        AutoCommit => 0,
-    },
-);
-
-$dbh->do( $sql->set_transaction_model );
-$dbh->commit;
-
-my $lxs   = Sys::Statistics::Linux::DiskUsage->new;
-
-while (1) {
-    my $query = $dbh->prepare_cached("INSERT INTO mount VALUES(?, ?, ?)");
-    $dbh->do("DELETE FROM mount");
-
-    my $stats = $lxs->get;
-    foreach my $dev (keys %$stats) {
-        my $mnt = $stats->{$dev};
-        my %mount;
-        $query->execute(@$mnt{qw( mountpoint total usage )});
+$SIG{TERM} = sub { unlink_pid_file($pidfile); exit(); };
+$SIG{INT}  = $SIG{TERM};
+$SIG{HUP}  = sub { $c = read_rcfile($rcfile) }; 
+
+my $dbh = setup_db(
+        db      => $db,
+        dbuser  => $dbuser,
+        dbpass  => $dbpass,
+    );
+
+poll_mounts(
+        dbh             => $dbh,
+        poll_interval   => $poll_interval,
+        debug           => $debug,
+    ) or die "poll_mounts() should not have returned";
+
+sub poll_mounts
+{
+    my %p = @_;
+
+    my $dbh             = $p{dbh} or return;
+    my $poll_interval   = $p{poll_interval} || 60;
+    my $debug           = $p{debug} || 0;
+
+    my $lxs = Sys::Statistics::Linux::DiskUsage->new;
+
+    while (1) {
+        # list of mount points to stat so that the automounter will mount these
+        # volumes if they have been unmounted.
+        stat_dirs($mounts);
+
+        my $query = $dbh->prepare_cached("INSERT INTO mount VALUES(?, ?, ?)");
+        $dbh->do("DELETE FROM mount");
+        print "flushed mount table\n" if $debug;
+
+        my $stats = $lxs->get;
+        foreach my $dev (keys %$stats) {
+            my $mnt = $stats->{$dev};
+            my %mount;
+            $query->execute(@$mnt{qw( mountpoint total usage )});
+            print "adding $mnt->{mountpoint} to db\n" if $debug;
+        }
+
+        $dbh->commit;
+
+        sleep $poll_interval;
     }
-
+}
+
+sub read_rcfile
+{
+    my $rcfile = shift;
+
+    return unless defined $rcfile;
+
+    if (!-f $rcfile) {
+        open(my $fh, '>', $rcfile) or die "can't open file: $!";
+        close($fh) or die "can't close file:$!";
+    }
+
+    return Config::YAML->new(
+            config => $rcfile,
+            output => $rcfile,
+    );
+}
+
+
+sub setup_db
+{
+    my %p = @_;
+
+    return unless defined $p{db}
+              and defined $p{dbuser}
+              and defined $p{dbpass};
+
+    my $sql = Nebulous::Server::SQL->new;
+
+    my $dbh = DBI->connect(
+        "DBI:mysql:database=$p{db}:host=localhost",
+        $p{dbuser},
+        $p{dbpass},
+        {
+            RaiseError => 1,
+            PrintError => 1,
+            AutoCommit => 0,
+        },
+    );
+
+    $dbh->do( $sql->set_transaction_model );
     $dbh->commit;
 
-    sleep $POLL_INTERVAL;
-}
+    return $dbh;
+}
+
+
+sub stat_dirs
+{
+    my $mounts = shift;
+
+    return unless defined $mounts;
+
+    foreach my $path (@$mounts) {
+        stat File::Spec->canonpath($path) or warn "can not stat path: $path";
+        print "stated $path\n" if $debug;
+    }
+}
+
+#
+# This function, originally named check_pid_file() was copied from
+# Net::Server::Daemonize '0.05' licensed under the Perl license.  It has been
+# renamed and modified to kill off process who's PID value is stored in pidfile.
+#
+
+sub kill_pid_file {
+  my $pid_file = shift;
+
+  ### no pid_file = return success
+  return 1 unless -e $pid_file;
+
+  ### get the currently listed pid
+  if( ! open(_PID,$pid_file) ){
+    die "Couldn't open existant pid_file \"$pid_file\" [$!]\n";
+  }
+  my $_current_pid = <_PID>;
+  close _PID;
+  my $current_pid = $_current_pid =~ /^(\d{1,10})/ ? $1 : die "Couldn't find pid in existing pid_file";
+
+  my $exists = undef;
+
+  ### try a proc file system
+  if( -d '/proc' ) {
+    $exists = -e "/proc/$current_pid";
+
+  ### try ps
+  #}elsif( -x '/bin/ps' ){ # not as portable
+  # the ps command itself really isn't portable
+  # this follows BSD syntax ps (BSD's and linux)
+  # this will fail on Unix98 syntax ps (Solaris, etc)
+  }elsif( `ps h o pid p $$` =~ /^\s*$$\s*$/ ){ # can I play ps on myself ?
+    $exists = `ps h o pid p $current_pid`;
+
+  }
+
+  ### running process exists, ouch
+    if( $exists ){
+
+        if( $current_pid == $$ ){
+            warn "Pid_file created by this same process. Doing nothing.\n";
+            return 1;
+        }else{
+            kill 'TERM', $current_pid
+                or die "Failed to signal process ($current_pid)";
+            unlink $pid_file || die "Couldn't remove pid_file \"$pid_file\" [$!]\n";
+            return 1;
+
+        }
+    }
+}
+
+__END__
+
+=pod
+
+=head1 NAME
+
+nebdiskd - Nebulous mounted volume capacity monitoring daemon
+
+=head1 SYNOPSIS
+
+    nebdiskd [--db <db name>] [--user <db username>] [--pass <db password>] [--debug] [--pidfile <filename>] [--stop] [--restart] [--verbose]
+
+=head1 DESCRIPTION
+
+This program looks for mounted volumes, at a configurable interval, and records
+statistics about them into a database.
+
+=head1 OPTIONS
+
+=over 4
+
+=item * --db|-d <db name>
+
+Name of database (C<namespace>) to write too.
+
+Optional if defined in the F<.nebdiskdrc> file or the appropriate environment
+variable is set.
+
+=item * --user|-u <db username>
+
+Username to authenticate with.
+
+Optional if defined in the F<.nebdiskdrc> file or the appropriate environment
+variable is set.
+
+=item * --pass|-p <db password>
+
+Password to authenticate with.
+
+Optional if defined in the F<.nebdiskdrc> file or the appropriate environment
+variable is set.
+
+=item * --debug
+
+This flag prevents the program from "daemonizing" so output can be sent to
+C<stdout>/C<stderr> and a debugger used on the running process.
+
+=item * --pidfile <filename>
+
+Filename to log the running daemon's PID too.
+
+Optional, if this option is omitted and no value is defined in the
+F<.nebdiskrc> then no pidfile is created.
+
+=item * --stop|-s
+
+Uses the pidfile to kill an already running daemon.
+
+=item * --restart|-r
+
+Uses the pidfile to kill an already running daemon and then starts a new
+instance.
+
+=item * --verbose|-r
+
+Turns on informational/debugging messages to be sent to the
+C<stderr>/C<stdout>.  This option is probably not very usefully unless combined
+with C<--debug>.
+
+=back
+
+=head1 ENVIRONMENT
+
+These environment variables may be used in place of the specified command line
+options.  All command line option will override the corresponding environment
+value.
+
+=over 4
+
+=item * C<NEB_DB>
+
+Equivalent to --db|-d
+
+=item * C<NEB_USER>
+
+Equivalent to --user|-u
+
+=item * C<NEB_PASS>
+
+Equivalent to --pass|-p 
+
+=back
+
+=head1 RCFILE
+
+This program will attempt to read an C<rcfile> from F<$HOME/.nebdiskrc> and if
+found will use it's values to override program defaults.  Please not that the
+precedence for values is: command line, rcfile, environment variables.
+
+The format of the C<rcfile> is in L<YAML> format and uses the following values:
+
+    ---
+    db: nebulous
+    dbpass: '@neb@'
+    dbuser: nebulous
+    mounts:
+      - /mnt
+      - /tmp
+      - /usr
+    pidfile: /var/tmp/nebdiskd
+    poll_interval: 5
+
+The values C<db>, C<dbpass>, C<dbuser>, and C<pidfile> have the same semantics
+as their command line and/or environment variable equivalents.
+
+=over 4
+
+=item * C<mounts>
+
+A list of "paths" to C<stat(2)> before mounted volumes are polled.  The propose
+of this option is to attempt to keep "automounted" volumes mounted while this
+program is running.
+
+This value may be omitted or left blank.
+
+=item * C<poll_interval>
+
+The number of seconds to wait between checks for mounted volumes.
+
+This value may be omitted or left blank.  The default value is C<60>s.
+
+=back
+
+=head1 CREDITS
+
+Just me, myself, and I.
+
+=head1 SUPPORT
+
+Please contact the author directly via e-mail.
+
+=head1 AUTHOR
+
+Joshua Hoblitt <jhoblitt@cpan.org>
+
+=head1 COPYRIGHT
+
+Copyright (C) 2007  Joshua Hoblitt.  All rights reserved.
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place - Suite 330, Boston, MA  02111-1307, USA.
+
+The full text of the license can be found in the L<perlgpl> Pod as supplied
+with Perl 5.8.1 and later.
+
+=head1 SEE ALSO
+
+L<Nebulous::Server>, L<YAML>
+
+=cut

trunk/Nebulous/Build.PL

@@ -78 +78 @@
     create_makefile_pl  => 'passthrough',
     requires            => {
+        'Config::YAML'          => '1.42',
         'URI'                   => '1.30',
         'SOAP::Lite'            => '0.69',

trunk/Nebulous/bin/nebdiskd

@@ -3 +3 @@
 # Copyright (C) 2007  Joshua Hoblitt
 # 
-# $Id: nebdiskd,v 1.1 2007-02-23 01:10:57 jhoblitt Exp $
+# $Id: nebdiskd,v 1.2 2007-03-24 00:40:11 jhoblitt Exp $
 
 use strict;
@@ -11 +11 @@
 $VERSION = '0.02';
 
-use Net::Server::Daemonize qw(daemonize);
+use Config::YAML;
+use DBI;
+use File::Spec;
+use Nebulous::Server::SQL;
+use Net::Server::Daemonize qw( daemonize unlink_pid_file );
 use Sys::Statistics::Linux::DiskUsage;
-use DBI;
-use Nebulous::Server::SQL;
 
 use Getopt::Long qw( GetOptions :config auto_help auto_version );
 use Pod::Usage qw( pod2usage );
 
-my ($debug, $db, $dbuser, $dbpass);
-
-$db     = $ENV{'NEB_DB'} unless $db;
-$dbuser = $ENV{'NEB_USER'} unless $dbuser;
-$dbpass = $ENV{'NEB_PASS'} unless $dbpass;
-
-our $POLL_INTERVAL = 5;
-
+my ($debug, $db, $dbuser, $dbpass, $pidfile, $stop, $restart, $verbose);
 GetOptions(
-    'debug|d'   => \$debug,
-    'db=s'      => \$db,
-    'user=s'    => \$dbuser,
-    'pass=s'    => \$dbpass,
+    'debug'     => \$debug,
+    'db|d=s'    => \$db,
+    'user|u=s'  => \$dbuser,
+    'pass|p=s'  => \$dbpass,
+    'pidfile=s' => \$pidfile,
+    'stop|s'    => \$stop,
+    'restart|r' => \$restart,
+    'verbose|v' => \$verbose,
 ) || pod2usage( 2 );
+
+my $rcfile = "$ENV{HOME}/.nebdiskrc";
+$rcfile = File::Spec->canonpath($rcfile);
+
+my $c = read_rcfile($rcfile);
+
+$db     ||= $c->get_db      || $ENV{'NEB_DB'};
+$dbuser ||= $c->get_dbuser  || $ENV{'NEB_USER'};
+$dbpass ||= $c->get_dbpass  || $ENV{'NEB_PASS'};
+$pidfile ||= $c->get_pidfile || "/var/tmp/nebdiskd";
+my $mounts = $c->get_mounts;
+my $poll_interval = $c->get_poll_interval || 5;
+
+if ($restart || $stop) {
+    my $status = kill_pid_file($pidfile);
+    exit($status) if $stop;
+}
+
+$c->set_db($db);
+$c->set_dbuser($dbuser);
+$c->set_dbpass($dbpass);
+$c->set_pidfile($pidfile);
+$c->set_poll_interval($poll_interval);
+$c->write;
 
 pod2usage( -msg => "Unknown option: @ARGV", -exitval => 2 ) if @ARGV;
@@ -39 +62 @@
 
 daemonize(
-    'jhoblitt', # User
-    'wheel',    # Group
-    undef       # PID file
+    $<,     # User
+    $),     # Group
+    $pidfile,  # PID file
 ) unless $debug;
 
-my $sql = Nebulous::Server::SQL->new;
-
-my $dbh = DBI->connect(
-    "DBI:mysql:database=$db:host=localhost",
-    $dbuser,
-    $dbpass,
-    {
-        RaiseError => 1,
-        PrintError => 0,
-        AutoCommit => 0,
-    },
-);
-
-$dbh->do( $sql->set_transaction_model );
-$dbh->commit;
-
-my $lxs   = Sys::Statistics::Linux::DiskUsage->new;
-
-while (1) {
-    my $query = $dbh->prepare_cached("INSERT INTO mount VALUES(?, ?, ?)");
-    $dbh->do("DELETE FROM mount");
-
-    my $stats = $lxs->get;
-    foreach my $dev (keys %$stats) {
-        my $mnt = $stats->{$dev};
-        my %mount;
-        $query->execute(@$mnt{qw( mountpoint total usage )});
+$SIG{TERM} = sub { unlink_pid_file($pidfile); exit(); };
+$SIG{INT}  = $SIG{TERM};
+$SIG{HUP}  = sub { $c = read_rcfile($rcfile) }; 
+
+my $dbh = setup_db(
+        db      => $db,
+        dbuser  => $dbuser,
+        dbpass  => $dbpass,
+    );
+
+poll_mounts(
+        dbh             => $dbh,
+        poll_interval   => $poll_interval,
+        debug           => $debug,
+    ) or die "poll_mounts() should not have returned";
+
+sub poll_mounts
+{
+    my %p = @_;
+
+    my $dbh             = $p{dbh} or return;
+    my $poll_interval   = $p{poll_interval} || 60;
+    my $debug           = $p{debug} || 0;
+
+    my $lxs = Sys::Statistics::Linux::DiskUsage->new;
+
+    while (1) {
+        # list of mount points to stat so that the automounter will mount these
+        # volumes if they have been unmounted.
+        stat_dirs($mounts);
+
+        my $query = $dbh->prepare_cached("INSERT INTO mount VALUES(?, ?, ?)");
+        $dbh->do("DELETE FROM mount");
+        print "flushed mount table\n" if $debug;
+
+        my $stats = $lxs->get;
+        foreach my $dev (keys %$stats) {
+            my $mnt = $stats->{$dev};
+            my %mount;
+            $query->execute(@$mnt{qw( mountpoint total usage )});
+            print "adding $mnt->{mountpoint} to db\n" if $debug;
+        }
+
+        $dbh->commit;
+
+        sleep $poll_interval;
     }
-
+}
+
+sub read_rcfile
+{
+    my $rcfile = shift;
+
+    return unless defined $rcfile;
+
+    if (!-f $rcfile) {
+        open(my $fh, '>', $rcfile) or die "can't open file: $!";
+        close($fh) or die "can't close file:$!";
+    }
+
+    return Config::YAML->new(
+            config => $rcfile,
+            output => $rcfile,
+    );
+}
+
+
+sub setup_db
+{
+    my %p = @_;
+
+    return unless defined $p{db}
+              and defined $p{dbuser}
+              and defined $p{dbpass};
+
+    my $sql = Nebulous::Server::SQL->new;
+
+    my $dbh = DBI->connect(
+        "DBI:mysql:database=$p{db}:host=localhost",
+        $p{dbuser},
+        $p{dbpass},
+        {
+            RaiseError => 1,
+            PrintError => 1,
+            AutoCommit => 0,
+        },
+    );
+
+    $dbh->do( $sql->set_transaction_model );
     $dbh->commit;
 
-    sleep $POLL_INTERVAL;
-}
+    return $dbh;
+}
+
+
+sub stat_dirs
+{
+    my $mounts = shift;
+
+    return unless defined $mounts;
+
+    foreach my $path (@$mounts) {
+        stat File::Spec->canonpath($path) or warn "can not stat path: $path";
+        print "stated $path\n" if $debug;
+    }
+}
+
+#
+# This function, originally named check_pid_file() was copied from
+# Net::Server::Daemonize '0.05' licensed under the Perl license.  It has been
+# renamed and modified to kill off process who's PID value is stored in pidfile.
+#
+
+sub kill_pid_file {
+  my $pid_file = shift;
+
+  ### no pid_file = return success
+  return 1 unless -e $pid_file;
+
+  ### get the currently listed pid
+  if( ! open(_PID,$pid_file) ){
+    die "Couldn't open existant pid_file \"$pid_file\" [$!]\n";
+  }
+  my $_current_pid = <_PID>;
+  close _PID;
+  my $current_pid = $_current_pid =~ /^(\d{1,10})/ ? $1 : die "Couldn't find pid in existing pid_file";
+
+  my $exists = undef;
+
+  ### try a proc file system
+  if( -d '/proc' ) {
+    $exists = -e "/proc/$current_pid";
+
+  ### try ps
+  #}elsif( -x '/bin/ps' ){ # not as portable
+  # the ps command itself really isn't portable
+  # this follows BSD syntax ps (BSD's and linux)
+  # this will fail on Unix98 syntax ps (Solaris, etc)
+  }elsif( `ps h o pid p $$` =~ /^\s*$$\s*$/ ){ # can I play ps on myself ?
+    $exists = `ps h o pid p $current_pid`;
+
+  }
+
+  ### running process exists, ouch
+    if( $exists ){
+
+        if( $current_pid == $$ ){
+            warn "Pid_file created by this same process. Doing nothing.\n";
+            return 1;
+        }else{
+            kill 'TERM', $current_pid
+                or die "Failed to signal process ($current_pid)";
+            unlink $pid_file || die "Couldn't remove pid_file \"$pid_file\" [$!]\n";
+            return 1;
+
+        }
+    }
+}
+
+__END__
+
+=pod
+
+=head1 NAME
+
+nebdiskd - Nebulous mounted volume capacity monitoring daemon
+
+=head1 SYNOPSIS
+
+    nebdiskd [--db <db name>] [--user <db username>] [--pass <db password>] [--debug] [--pidfile <filename>] [--stop] [--restart] [--verbose]
+
+=head1 DESCRIPTION
+
+This program looks for mounted volumes, at a configurable interval, and records
+statistics about them into a database.
+
+=head1 OPTIONS
+
+=over 4
+
+=item * --db|-d <db name>
+
+Name of database (C<namespace>) to write too.
+
+Optional if defined in the F<.nebdiskdrc> file or the appropriate environment
+variable is set.
+
+=item * --user|-u <db username>
+
+Username to authenticate with.
+
+Optional if defined in the F<.nebdiskdrc> file or the appropriate environment
+variable is set.
+
+=item * --pass|-p <db password>
+
+Password to authenticate with.
+
+Optional if defined in the F<.nebdiskdrc> file or the appropriate environment
+variable is set.
+
+=item * --debug
+
+This flag prevents the program from "daemonizing" so output can be sent to
+C<stdout>/C<stderr> and a debugger used on the running process.
+
+=item * --pidfile <filename>
+
+Filename to log the running daemon's PID too.
+
+Optional, if this option is omitted and no value is defined in the
+F<.nebdiskrc> then no pidfile is created.
+
+=item * --stop|-s
+
+Uses the pidfile to kill an already running daemon.
+
+=item * --restart|-r
+
+Uses the pidfile to kill an already running daemon and then starts a new
+instance.
+
+=item * --verbose|-r
+
+Turns on informational/debugging messages to be sent to the
+C<stderr>/C<stdout>.  This option is probably not very usefully unless combined
+with C<--debug>.
+
+=back
+
+=head1 ENVIRONMENT
+
+These environment variables may be used in place of the specified command line
+options.  All command line option will override the corresponding environment
+value.
+
+=over 4
+
+=item * C<NEB_DB>
+
+Equivalent to --db|-d
+
+=item * C<NEB_USER>
+
+Equivalent to --user|-u
+
+=item * C<NEB_PASS>
+
+Equivalent to --pass|-p 
+
+=back
+
+=head1 RCFILE
+
+This program will attempt to read an C<rcfile> from F<$HOME/.nebdiskrc> and if
+found will use it's values to override program defaults.  Please not that the
+precedence for values is: command line, rcfile, environment variables.
+
+The format of the C<rcfile> is in L<YAML> format and uses the following values:
+
+    ---
+    db: nebulous
+    dbpass: '@neb@'
+    dbuser: nebulous
+    mounts:
+      - /mnt
+      - /tmp
+      - /usr
+    pidfile: /var/tmp/nebdiskd
+    poll_interval: 5
+
+The values C<db>, C<dbpass>, C<dbuser>, and C<pidfile> have the same semantics
+as their command line and/or environment variable equivalents.
+
+=over 4
+
+=item * C<mounts>
+
+A list of "paths" to C<stat(2)> before mounted volumes are polled.  The propose
+of this option is to attempt to keep "automounted" volumes mounted while this
+program is running.
+
+This value may be omitted or left blank.
+
+=item * C<poll_interval>
+
+The number of seconds to wait between checks for mounted volumes.
+
+This value may be omitted or left blank.  The default value is C<60>s.
+
+=back
+
+=head1 CREDITS
+
+Just me, myself, and I.
+
+=head1 SUPPORT
+
+Please contact the author directly via e-mail.
+
+=head1 AUTHOR
+
+Joshua Hoblitt <jhoblitt@cpan.org>
+
+=head1 COPYRIGHT
+
+Copyright (C) 2007  Joshua Hoblitt.  All rights reserved.
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place - Suite 330, Boston, MA  02111-1307, USA.
+
+The full text of the license can be found in the L<perlgpl> Pod as supplied
+with Perl 5.8.1 and later.
+
+=head1 SEE ALSO
+
+L<Nebulous::Server>, L<YAML>
+
+=cut