ps-watcher/ps-watcher.in.in

#!@PERL@ -w
# -*- Perl -*-
use diagnostics;
my $vcid='$Id: ps-watcher.in.in,v 1.62 2008/12/23 11:09:24 rockyb Exp $ ';
# See usage subroutine or perlpod documentation below.

# Copyright (C) 2000, 2002, 2003, 2004, 2005, 2006, 2008 
# Rocky Bernstein, email: rocky@gnu.org
#
# 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., 675 Mass Ave, Cambridge, MA 02139, USA.

use vars qw($program $ps_cmd $ps_cmdfull $ps_fullcmd_fmt @ps_vars $ps_dvars
	    $0 $logopened $ps_args_fmt $args
            $count $pid $command $ps_arg_opts $DEVNULL %opts
           );
use strict;
BEGIN { require 5.00503 }

sub usage($) {
  my ($full_help) = @_;

  print "
usage: 

   $program [OPTIONS..]

$program can be used to monitor various processes based on ps-like
information.

options: 
  --help              -- print this help and exit
  --doc               -- extract and print complete documentation and exit
  --version           -- show a CVS version string and exit
  --debug *n*         -- give debugging output. The higher the
                         number, the more the output
  --run | --norun     -- do/don't run actions
                         go through the motions as though we were going to
  --log  [*logfile*]  -- Set a log file for this program. If option given
                         but no logfile, then use STDERR. Default is 
                         no error log file.
  --syslog | --nosyslog
                      -- send or don't send error output to syslog
                         Default is to send to syslog.
  --config *cnf file* -- specify configuration file.

  --daemon | --nodaemon 
                      -- do or don't become a daemon. Default daemonize.
  --sleep  *time*     -- sleep interval between iterations. The default is
                         $opts{sleep_interval} seconds.
  --path path         -- executable search path to use in running commands

  --ps-prog *program* -- command that gets ps information. The default is:
                         $opts{ps_prog}
  --ps-pids-opt *ps opts* 
                      -- ps options that lists pids and commands. The
                         default is: $opts{ps_pid_opts}
";

  if ($full_help) {
      print "
General operation: 

Periodically a list of processes obtained via ps. More precisely
each item in the list contains the process name (just what's listed in
the \"command\" field, not the full command and arguments) and its
process id (pid). A configuration file specifies a list of Perl
regular-expression patterns to match the process names against. For
each match, a Perl expression specified for that pattern is
evaluated. The evaluated expression can refer to variables which are
set by ps and pertain to the matched process(es), for example the
amount memory consumed by the process, or the total elapsed time. Some
other variables are set by the program, such as the number of times
the process is running. If the Perl expression for a matched pattern
evaluates true, then an action can be run such as killing the program,
restarting it, or mailing an alert.

This program can be used to ensure a daemon hasn't died or ensure it
is not running too many times. It might be used to determine when a
process has consumed too many resources (for example due to a memory
leak).

The following variables can be used in patterns or actions:
\t".  '$' . join("\n\t\$", @ps_vars) .
"
  The following is a sample config file:

# Comments start with # or ; and go to the end of the line.

# The format for each entry is in Microsoft .INI form:
# [process-pattern]
# trigger = perl-expression
# action  = program-and-arguments-to-run

[httpd\$]
  trigger = \$count < 4
  action  = echo \"\$trigger fired -- You have \$count \$command sessions.\"

[em?cs]
trigger = \$vsz > 10
action  = echo \"Looks like you have a big \$command program: \$vsz KB\"

";
   }
   exit 100;
}

sub init();
sub podthis();
sub process_options();
sub show_version();
sub daemonize();
sub eval_trigger_action($$$);
sub make_the_rounds($);
sub elapsed2secs($);
sub logger($);
sub debug_log($$);
sub gather_psinfo();
sub read_config($);
sub check_config_file($);
sub run_trigger($$$);

init();
process_options();

# Unfurl the banner...
logger("Starting: $vcid");

my $cfg=read_config($opts{conf_file});

if (!defined($cfg)) {
  for my $line (@Config::IniFiles::errors) {
    logger($line);
  }
  exit 2;
}

if ($opts{daemon}) {
  daemonize();
}

install_handlers();

do {
  make_the_rounds($cfg);
  sleep $opts{sleep_interval} if $opts{sleep_interval} > 0;
  check_config_file($opts{conf_file});
} until ($opts{sleep_interval} < 0) ;
if ($opts{syslog}) {
 use Sys::Syslog;
 closelog;
}
exit 0;

# Evaluates the trigger and if that's true also performs
# an action. 1 is returned if the action was performed, 
# zero otherwise.
sub eval_trigger_action($$$) {
    my ($trigger,$action,$perl_action) = @_;
    my $etrigger=$trigger;
    # It is a pain to predeclare all of the variables assigned
    # by ps which is OS and ps specific. So we'll allow anything.
    # Likewise, we'll allow it occur in $action.
    no strict; 
    if ($trigger ne '1') {
	$etrigger =~ s/"/\\"/g;
	debug_log("trigger before substitution: $etrigger", 2);
	$etrigger = eval qq/"$trigger"/;
    }
    debug_log("trigger after substitution: $etrigger", 2);
    if (eval ($etrigger)) {
	if (defined($perl_action)) {
	    debug_log("running Perl_action: $perl_action", 2);
	    eval($perl_action) if $opts{run};
	}
	if (defined($action)) {
	    debug_log("action before substitution: $action", 2);
	    my $eaction=$action;
	    $eaction =~ s/"/\\"/g;
	    $eaction = eval qq/"$eaction"/;
	    debug_log("action after substitution: $eaction", 2);
	    my $output=`$eaction` if $opts{run};
	    chomp($output);
	    logger($output) if $output;
	}
	return 1;
    }
    return 0;
}

# Perform a round over the process_patterns comparing against the
# process info to see if anything's stirring.
sub make_the_rounds($) {
  my $cfg = $_[0];
  my @ps_info=gather_psinfo();
  foreach our $ps_pat ($cfg->Sections()) {
    debug_log("process pattern: /$ps_pat/", 1);
    my @selected_ps;
    my $in_prolog_epilog=0;
    my $trigger     = $cfg->val($ps_pat, 'trigger') || '1';
    my $action      = $cfg->val($ps_pat, 'action');
    my $perl_action = $cfg->val($ps_pat, 'perl-action');
    my $occurs      = $cfg->val($ps_pat, 'occurs') || "first";
    local $count;
    if ($ps_pat =~ /^\$PROLOG/ || $ps_pat =~ /\$EPILOG/) {
	# Set to run trigger below.
	$count  = @ps_info;
	$in_prolog_epilog=1;
    } else {
	@selected_ps = grep(/$ps_pat/, @ps_info);
	$count = @selected_ps; 
	debug_log("count for /$ps_pat/: $count", 2);
    }
    if ($in_prolog_epilog) {
	# execute trigger
	eval_trigger_action($trigger, $action, $perl_action);
    } elsif ($occurs =~ /none/i) {
      if ($count eq 0) {
	  # execute the trigger anyway
	  eval_trigger_action($trigger, $action, $perl_action);
      }
    } elsif ($count gt 0) {
    TRIGGER:
      foreach (@selected_ps) {
	next if !/\s*(\d+)\s+(\S+)/;
        local($pid, $command) = /\s*(\d+)\s+(\S+)/;
        if ($pid !~ /\d+/) {
          logger("Something wrong with ps format:\n$_");
          next;
        }

        my $ps_fullcmd = sprintf $ps_fullcmd_fmt, $pid;
        my @output     = `$ps_fullcmd`;
        my $output='';
	if (@output == 1) {
	  # Got one line of output - good.
	  $output=$output[0];
	  # Make sure though we don't just have a title line. 
	  # One of the fields should be just digits, e.g. ppid, uid, gud...
	  next if $output !~ m{\s+\d+\s+};
        } elsif (@output == 2 && @PS_NO_NULL_HEADER@) {
	  # Got two lines of output - we are running a ps where
          #  we can't remove the title line?
	  $output=$output[1];
        } elsif (@output > 1 && @PS_CAN_RETURN_MULTIPLE_LINES@) {
	  # Got multiple lines of output - we are running a ps which can
	  # do so. For example Solaris does this for a process that has many
	  # LWPs (light-weight processes).
	  $output=$output[0];
	} else {
          debug_log("Something wrong getting ps variables", 1);
	  next;
        }

	local $args = '';
	if ($ps_arg_opts) {
	  my $ps_argscmd = sprintf $ps_args_fmt, $pid;
          my @output     = `$ps_argscmd`;
	  if (@output == 1) {
  	    $args=$output[0];
          } elsif (@output == 2 && @PS_NO_NULL_HEADER@) {
	    $args=$output[1];
	  } else {
            debug_log("Something wrong with getting command arguments", 1);
          }
	}

        # Process may have disappeared. In this case we'll get no 
	# output.
	next if !$output;

        # Add ' ' so split will junk first ps_dvars $junk.
        $output = ' ' . $output;
        my $perl_ps_assign = "$ps_dvars = split(/\\s+/, \$output)";
        { 
          # It is a pain to predeclare all of the variables assigned
          # by ps which is OS and ps specific. So we'll allow anything.
          # Likewise, we'll allow it occur in $action.
          no strict; 

	  # Escape backticks so that we don't inadvertently run
	  # the program. For example there could be a process named
	  # `/tmp/evilcommand` (with backticks). Thanks to Randal
	  # Schwartz for noticing the problem.
	  # Not sure if there are other things to watch out for.
	  # Although the Perl Cookbook suggests how to make system,
	  # safe, it is silent about making eval safe.
	  $command =~ s/`/\\`/g;

          if (eval ($perl_ps_assign)) {
	      my $evaled = eval_trigger_action($trigger, $action, 
					       $perl_action);
	      last TRIGGER if $evaled && $occurs eq 'first-trigger';
	      last TRIGGER if $occurs eq 'first';
          } else {
            logger("Something wrong with perl assignment: $perl_ps_assign");
            last TRIGGER;
	  }
        } # no strict
      } # foreach
    } # if $count
  }
}

# Initailize various variables variously.
sub init() {

  use File::Basename;
  $program          = basename($0); # Who am I today, anyway? 

  $DEVNULL = '/dev/null'; # And what do we do about non Unix?

  use constant MINS   => 60;
  use constant HOURS  => 60*60;
  use constant DAYS   => HOURS * 24;

  $opts{debug}        = 0;  # no debugging
  $opts{run}          = 1;  # run actions
  $opts{syslog}       = 1;  # Log errors to syslog
  $opts{logfile}      = $DEVNULL;  
  $opts{daemon}       = 1;  # Run as daemon;
  $opts{ps_prog}      = '@PS@';   # Where is ps? 
  $opts{ps_pid_opts}  = '@PS_PID_OPTS@';   # How do I get pids and commands?

  $ps_arg_opts  = '@PS_ARGS@';       # How do I get full process command?

  # List of all the fields from ps we will be able to use. Don't need
  # to list variables listed above. 
  @ps_vars = qw ( @PS_VARS@ 
);

  # Convert the above into an argument list like
  # ($junk, $user, ... )
  # The first argument ($junk) will be null and thrown out.
  $ps_dvars = '($junk,$' . join(',$', @ps_vars) . ')';

  $opts{sleep_interval} = 300;

}

# The bane of programming.
sub process_options() {
  use Getopt::Long;
  my(@opt_cf);
  $Getopt::Long::autoabbrev = 1;
  my($newstyle_config);

  my ($help, $long_help, $show_version);

  my $result = &GetOptions
    (
     'help'         => \$help,
     'doc'          => \$long_help,
     'version'      => \$show_version,
     'config=s'     => \$opts{conf_file},
     'debug=i'      => \$opts{debug}, 
     'path=s'       => \$ENV{PATH},
     'ps-pid-opts=s'=> \$opts{ps_pid_opts},
     'ps-prog=s'    => \$opts{ps_prog},
     'sleep=i'      => \$opts{sleep_interval},
     'log:s'        => \$opts{logfile},
     'syslog!'      => \$opts{syslog}, 
     'run!'         => \$opts{run}, 
     'daemon!'      => \$opts{daemon}, 
    );

  show_version() if $show_version;
  usage(1) if $help;
  podthis() if $long_help;

  # However specifying a configuration file is not. 
  # Nor can we deal with multiple configuration files or tolerate
  # option-processing errors. 
  usage(0) if !$result;

  # The option-specifier "--config" is optional...
  if (@ARGV && !defined($opts{conf_file})) {
    $opts{conf_file} = shift(@ARGV);
  } 
  
  # However we do have to give exactly one configurtion file. 
  if (!defined($opts{conf_file}) || @ARGV != 0) {
    print STDERR "$program: Please specify exactly one configuration file.\n";
    usage(0);
  }

  $ps_cmd = "$opts{ps_prog} $opts{ps_pid_opts}"; 
  my $ps_vars;
  if (@PS_CUSTOM_HEADER@) {
   $ps_vars = join('= -o ', @ps_vars) . '=';
  } else {
   $ps_vars = join(' -o ', @ps_vars);
  }

  if ('@PS_FULLCMD_FMT@') {
      $ps_fullcmd_fmt  = "@PS_FULLCMD_FMT@";
  } else {
      $ps_fullcmd_fmt  = "$opts{ps_prog} -p %d -o $ps_vars";
  }
  if ('@PS_ARGS_FMT@') {
      $ps_args_fmt     = "@PS_ARGS_FMT@";
  } else {
      $ps_args_fmt     = "$opts{ps_prog} -p %d $ps_arg_opts";
  }

  open STDIN, $DEVNULL   or die "Can't read $DEVNULL: $!";
  if ($opts{logfile} ne '') {
      open STDOUT, ">>$opts{logfile}" or 
	  die "Can't write STDOUT to $opts{logfile}: $!";
      open STDERR, ">>&STDOUT" or 
	  die "Can't write STDERR to $opts{logfile}: $!";
  }
}

# Signal handling..
sub install_handlers {
  $SIG{'QUIT'} = \&terminate;
  $SIG{'TERM'} = \&terminate;
  $SIG{'INT'}  = \&terminate;
  $SIG{'HUP'}  = \&null_handler;
  $SIG{'USR1'} = \&debug_up_handler;
  $SIG{'USR2'} = \&debug_down_handler;
}

# Used perhaps to break out of a deep sleep.
sub null_handler {
  my($signo) = @_;
  logger("Received signal: ${signo}");
}

# Increase verbosity of debugging.
sub debug_up_handler {
  my($signo) = @_;
  $opts{debug}++;
  logger("Received signal: ${signo}. Increasing debugging to $opts{debug}.");
}

# Decrease verbosity of debugging.
sub debug_down_handler {
  my($signo) = @_;
  $opts{debug}--;
  logger("Received signal: ${signo}. Decreasing debugging to $opts{debug}.");
}

# Signal handler to go down recording the signal.
sub terminate {
  my($signo) = @_;
  use Config;
  if (defined $Config{sig_name}) {
      my $i = 0; 
      my @signame;
      my %sig;
      foreach my $name (split(' ', $Config{sig_name})) {
	  $signame[$i] = $name;
	  $sig{$name} = $i;
	  $i++;
      }
      $signo = $sig{$signo} if exists($sig{$signo});
      if ($signo =~ m{\A\d+\Z} ) {
	  logger("Going down on $signame[$signo] (${signo}) signal. " .
		 "Have a nice day!");
      } 
  } else {
      logger("Going down on signal ${signo}). Have a nice day!");
  }

  $signo = 15 if $signo !~ m{\A\d+\Z};
  if ($opts{syslog}) {
      use Sys::Syslog;
      closelog;
  }
  exit $signo;
};

# Utility function for parsing/converting elapsed time into seconds.
sub elapsed2secs($) {
  $_ = $_[0];

  # Handle formats like:
  # 1-08:34:37  -- One day, 8 hours, 34 minutes, 37 seconds
  #   20:40:34  -- 20 hours, 40 minutes, 34 seconds
  #       0:00  -- 0 seconds.

  # 1-08:34.37  -- One day, 8 hours, 34 minutes, 37 seconds
  #   20:40.34  -- 20 hours, 40 minutes, 34 seconds
  #       5.03  -- 5 minutes, 3 seconds.
  #          5  -- 5 seconds.

  # Some easy cases.
  return -1 if !defined($_) || m{\A\s*\Z};
  return $_ if m{\A\d+\Z};

  # Originally had as one pattern and optional 
  # arguments but i got compaints about using
  # uninitialized variables even with "no diagonstics". Would rather
  # switch than fight.
  my $min_secs_pat = '(\d{1,2})[:.](\d\d)';
  if (m{
      (\d{1,2})-          # The number of days. e.g. 1- or 19- or blank
      (\d{1,2})[:.]       # The number of hrs. e.g. 01: or 23: or blank
      $min_secs_pat
      }x) {
      my ($days, $hours, $minutes, $secs) = ($1, $2, $3, $4);
      return ($days*DAYS + $hours*HOURS + $minutes*MINS + $secs);
  } elsif (m{
	   (\d{1,2})[:.]  # The number of hrs. e.g. 01: or 23: or blank
	   $min_secs_pat
	   }x) {
      my ($hours, $minutes, $secs) = ($1, $2, $3);
      return ($hours*HOURS + $minutes*MINS + $secs);
  } elsif (m{$min_secs_pat}) {
    my ($minutes, $secs) = ($1, $2);
    return ($minutes*MINS + $secs);
  } else {
    logger("Error in converting $_ to seconds");
    return -1;
  }
}

# Return time and PID as string in a common format
sub timestring() { 
    my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = 
	localtime(time);
    $mon++; 
    return sprintf( "%.2d/%.2d/%.2d %.2d:%.2d:%.2d %s[$$]", 
		    $mon, $mday, $year%100, $hour, $min, $sec, $program); 
}

# log error to syslog and print to STDERR.
sub logger($) {
  my($msg) = shift;

  if ($opts{syslog}) {
    if (!$logopened) {
      use Sys::Syslog;
      $logopened++;
      openlog($program,'cons,pid', 'err');
    }
    syslog('info', $msg);
  }
  if (defined($opts{logfile}) && $opts{logfile} ne $DEVNULL) {
    my $ts=timestring();
    print STDERR "$ts: $msg\n";
  }
}

sub debug_log($$) {
  my($msg, $level) = @_;
  logger("** debug ** $msg") if $opts{debug} >= $level;
}

sub gather_psinfo() {
  my @output=`$ps_cmd`;
  return @output;
}

# Show the CVS version id string and quit.
sub show_version() {
  print "$vcid
Copyright (C) 2000, 2002, 2003, 2004, 2006, 2008 Rocky Bernstein.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.
";
  exit 10;
}


sub daemonize() {
  chdir '/'                 or die "Can't chdir to /: $!";
  defined(my $pid = fork)   or die "Can't fork: $!";
  exit 0 if $pid;
  use POSIX qw(setsid);
  setsid()                  or die "Can't start a new session: $!";
  umask 0;
}

# Time configuration file was last read.
my $conf_time;

# Read a configuration file.
sub read_config($) {
  use Config::IniFiles;
  my($cf)=@_;
  if (!-f $cf || !-r _ || -z _ || !-T _) {
    logger("Unusable config file: <$cf>");
    return undef;
  } 

  # Save time we read the configuration file so we can check back
  # later to see if it changed.

  my($dev, $ino, $mode, $nlink, $uid, $gid, $rdev, $size,
     $atime, $mtime, $ctime) = stat $cf;
  $conf_time = $mtime;

  return new Config::IniFiles( -file => $cf );
}

# Check to see if any configuration file has changed 
# since the last time this routime was called.
# Updates global $conf_time.
sub check_config_file($) {
  my ($conf_file) = @_;
  my($dev, $ino, $mode, $nlink, $uid, $gid, $rdev, $size,
     $atime, $mtime, $ctime) = stat $opts{conf_file}; 
  if ( defined($conf_time) && defined($mtime) && $conf_time < $mtime ) { 
    logger("Configuration file $conf_file modified; re-reading...");
    $cfg = read_config($conf_file);
  }
}

sub run_trigger($$$) {
  my($trigger, $action, $count) = @_;
  my $etrigger=$trigger;
  if ($trigger ne '1') {
    $etrigger =~ s/"/\\"/g;
    debug_log("trigger before substitution: $etrigger", 2);
    $etrigger = eval qq/"$trigger"/;
  }
  debug_log("trigger after substitution: $etrigger", 2);
  if (eval ($etrigger)) {
    debug_log("action before substitution: $action", 2);
    my $eaction=$action;
    $eaction =~ s/"/\\"/g;
    $eaction = eval qq/"$eaction"/;
    debug_log("action after substitution: $eaction", 2);
    my $output=`$eaction` if $opts{run};
    chomp($output);
    logger($output) if $output;
  }
}

sub podthis() {
  use Pod::Text;
  $^W = 0;
  pod2text $0;
  exit 101;
}

#--------------------------------------------------
=pod

=head1 NAME

@PACKAGE@ - monitors various processes based on ps-like information.


=head1 SYNOPSIS

B<@PACKAGE@> [I<options>...]
            [C<--config>] I<config-file>

=head1 DESCRIPTION

Periodically a list of processes obtained via C<ps>. More precisely
each item in the list contains the process name (just what's listed in
the "cmd" field, not the full command and arguments) and its process
id (pid). A configuration file specifies a list of Perl
regular-expression patterns to match the processes against. For each
match, a Perl expression specified for that pattern is evaluated. The
evaluated expression can refer to variables which are set by ps and
pertain to the matched process(es), for example the amount memory
consumed by the process, or the total elapsed time. Some other
variables are set by the program, such as the number of times the
process is running. If the Perl expression for a matched pattern
evaluates true, then an action can be run such as killing the program,
restarting it, or mailing an alert, or running some arbitrary Perl
code.

Some things you might want to watch a daemon or process for:

=over 2

=item *

check that it is running (hasn't died)

=item *

ensure it is not running too many times

=item *

isn't consuming too much memory (perhaps a memory leak), or I/O

=back

Some actions you might want to take:

=over 2

=item *

restart a process

=item *

kill off rampant processes

=item *

send an alert about any of the conditions listed above

=back

Depending on options specfied, this program can be run as a daemon,
run once (which is suitable as a C<cron> job), or run not as a daemon
but still continuously (which may be handy in testing the program or
your configuration).

=head2 OPTIONS

=over 4

=item --help

Print a usage message on standard error and exit with a return code
of 100.

Z<>

=item --doc

Extact the full documentation that you are reading now, print it and
exit with a return code of 101.

Z<>

=item --version

Print the version release on standard output and exit with a return
code of 10.

Z<>

=item --debug I<number> 

Give debugging output. The higher the number, the more the output. The
default is 0 = none. 2 is the most debugging output.

=item [--config] I<configuration file>

Specify configuration file. .

See L<CONFIGURATION FILE FORMAT> below for information on the format
of the configuration file and L<EXAMPLE CONFIGURATION> for a complete
example of a configuration file.

Z<>

=item --log [I<log file>]

Send or don't send error and debugging output to a log file. If option
is given but no logfile is specified, then use STDERR. The default is
no error log file.  See also --syslog below.

Z<>

=item --syslog | --nosyslog

Send or don't send error and debugging output to syslog. The default
is to syslog error and debug output.

Z<>

=item --daemon | --nodaemon

Run or don't as a daemon.

Z<>

=item --path I<search-path>

Specify the executable search path used in running commands.

=item --ps-prog I<program>

One can specify the command that gives ps information. By default, the
command is F<@PS@>.

Z<>

=item --run | --norun  

do/don't run actions go through the motions as though we were going
to. This may be useful in debugging.

Z<>

=item --sleep I<interval in seconds>

It is expected that one might want to run @PACKAGE@ over and over
again. In such instances one can specify the amount of time between
iterations with this option.

If a negative number is specified the program is run only once.

Z<>

=back

=head2 CONFIGURATION FILE MODIFICATION AND SIGNAL HANDLING

Periodically @PACKAGE@ checks to see if the configuration file
that it was run against has changed. If so, the program rereads the
configuration file.

More precisely, the checks are done after waking up from a slumber.
If the sleep interval is long (or if you are impatient), you can
probably force the program to wake up using a HUP signal.

At any time you can increase the level of debug output by sending a
USR1 signal to the @PACKAGE@ process. Similarly you can decrease the
level of debug output by sending the process a USR2 signal.

It is recommended that you terminate @PACKAGE@ via an INT, TERM, or QUIT
signal.

=head1 CONFIGURATION FILE FORMAT

The format of a configuration file is a series of fully qualified
filenames enclosed in square brackets followed by a number of
parameter lines. Each parameter line has a parameter name followed by
an "equal" sign and finally value. That is:

 # This is a comment line
 ; So is this.
 [process-pattern1]
  parameter1 = value1
  parameter2 = value2

 [process-pattern2]
  parameter1 = value3
  parameter2 = value4

Comments start with # or ; and take effect to the end of the line.

This should be familiar to those who have worked with text-readible
Microsoft C<.INI> files.

Note process patterns, (F<process-pattern1> and F<process-pattern2>
above) must be unique. If there are times when you may want to
refer to the same process, one can be creative to make these unique.
e.g. F<cron> and F<[c]ron> which refer to the same process even
though they I<appear> to be different.

As quoted directly from the Config::IniFiles documentation:

Multiline or multivalued fields may also be defined ala UNIX
"here document" syntax:

  Parameter=<<EOT
  value/line 1
  value/line 2
  EOT

You may use any string you want in place of "EOT".  Note
that what follows the "<<" and what appears at the end of
the text I<must> match exactly, including any trailing
whitespace.

There are two special "process patterns": $PROLOG and $EPILOG, the
former should appear first and the latter last.

You can put perl code to initialize variables here and do cleanup
actions in these sections using "perl-action." 

A description of parameters names, their meanings and potential values
follows.

=over

=item trigger

This parameter specifies the condition on which a process action is
fired.  The condition is evaluated with Perl eval() and should
therefore return something which is equivalent to "true" in a Perl
expression.

If no trigger is given in a section, true or 1 is assumed and
the action is unconditionally triggered.

Example: 

  # Match if httpd has not spawned enough (<4) times. NFS and databases
  # daemons typically spawn child processes.  Since the program
  # matches against the command names, not commands and arguments,
  # something like: ps -ef | grep httpd won't match the below.
  # If you want to match against the command with arguments, see
  # the example with $args below.
  [httpd$]
  trigger = $count <= 4

=item occurs

This parameter specifies how many times an action should be performed
on processes matching the section trigger. Acceptable values are
"every", "first", "first-trigger", and "none".

Setting the occurs value to "none" causes the the trigger to be
evaluated when there are no matching processes.  Although one might
think "$count == 0" in the action expression would do the same thing,
currently as coded this does not work.

Setting the occurs value to "first" causes the process-pattern rule to
be finished after handling the first rule that matches, whether or not the
trigger evaluated to true.

Setting the occurs value to "first-trigger" causes the process-pattern
rule to be finished after handling the first rule that matches I<and>
the trigger evaluates to true.

If the item parameter is not specified, "first" is assumed.

Examples:

  [.]
  occurs = first
  action = echo "You have $count processes running"

  # Note in the above since there is no trigger specified,
  #   occurs = first
  # is the same thing as 
  #   occurs = first-trigger

  [.?]
  trigger = $vsz > 1000
  occurs  = every
  action  = echo "Large program $command matches $ps_pat: $vsz KB"

  # Fire if /usr/sbin/syslogd is not running.
  # Since the program matches against the command names, not commands and
  # arguments, something like: 
  #   ps -ef | grep /usr/sbin/syslogd
  # won't match the below.
  [(/usr/sbin/)?syslogd]
  occurs = none
  action = /etc/init.d/syslogd start

=item action

This specifies the action, a command that gets run by the system
shell, when the trigger condition is evaluated to be true.

Example:

 action = /etc/init.d/market_loader.init restart

=item perl-action

This specifies Perl statements to be eval'd. This can be especially
useful in conjunction with $PROLOG and $EPILOG sections to make tests
across collections of process and do things which @PACKAGE@
would otherwise not be able to do.

Example:

  # A Perl variable initialization.
  # Since @PACKAGE@ runs as a daemon it's a good idea
  # to (re)initialize variables before each run.
  [$PROLOG]
    perl-action = $root_procs=0;

  # Keep track of how many root processes we are running
  [.*]
    perl-action = $root_procs++ if $uid == 0
    occurs  = every

  # Show this count.
  [$EPILOG]
    action  = echo "I counted $root_procs root processes"

=back

=head2 EXPANDED VARIABLES IN TRIGGER/ACTION CLAUSES

Any variables defined in the program can be used in pattern or
action parameters. For example, C<$program> can be used to refer to 
the name of this program @PACKAGE@.

The following variables can be used in either the pattern or action
fields.

=over

=item $action

A string containing the text of the action to run.

Z<>

=item $perl_action

A string containing the text of the perl_action to run.

Z<>

=item $ps_pat

The Perl regular expression specified in the beginning of the section.

Z<>

=item $command

The command that matched $ps_pat.

The Perl regular expression specified in the beginning of the section.
Normally processes will not have funny characters in them. Just in
case, backticks in $command are escaped.

Example: 

  # List processes other than emacs (which is a known pig) that use lots
  # of virtual memory

  [.*]
  trigger = $command !~ /emacs$/ && $vsz > 10
  action  = echo \"Looks like you have a big \$command program: \$vsz KB\"

Z<>

=item $count

The number of times the pattern matched. Presumably the number of
processes of this class running.

Z<>

=item $trigger

A string containing the text of the trigger.

=back

A list of variables specific to this program or fields commonly found in
C<ps> output is listed below followed by a description of the more
common ones. See also C<ps> for a more complete
description of the meaning of the field.

 @PS_VARS@

Beware though, in some situations ps can return multiple lines for a
single process and we will use just one of these in the trigger. In
particular, Solaris's C<ps> will return a line for each LWP (light-weight
process). So on Solaris, if a trigger uses variable lwp, it may or may
not match depending on which single line of the multiple C<ps> lines is
used.

Z<>

=over 

=item $args

The command along with its command arguments. It is possible that this
is might get truncated at certain length (if ps does likewise as is
the case on Solaris). 

Z<>

=item $ppid

The parent process id.

Z<>

=item $stime

The start time of the process.

Z<>

=item $etime

The end time of the process.

Z<>

=item $pmem

The process memory.

Z<>

=item $pcpu

The percent CPU utilization.

Z<>

=item $tty

The controlling tty.

Z<>

=item $vsz

Virtual memory size of the process

=back

=head2 OTHER THINGS IN TRIGGER CLAUSES

To make testing against elapsed time easier, a function C<elapse2sec()>
has been written to parse and convert elapsed time strings in the 
format C<dd-hh:mm:ss> and a number of seconds.

Some constants for the number of seconds in a minute, hour, or day
have also been defined. These are referred to as C<MINS>, C<HOURS>,
and C<DAYS> respectively and they have the expected definitions:

  use constant MINS   => 60;
  use constant HOURS  => 60*60;
  use constant DAYS   => HOURS * 24;

Here is an example of the use of C<elapsed2sec()>:

  # Which processes have been running for more than 3 hours?
  # Also note use of builtin-function elapsed2secs, variable $etime
  # and builtin-function HOURS
  [.]
    trigger = elapsed2secs('$etime') > 1*DAYS
    action  = echo "$command has been running more than 1 day ($etime)"
    occurs  = every

Please note the quotes around '$etime'.

=head1 EXAMPLE CONFIGURATION

  # Comments start with # or ; and go to the end of the line.

  # The format for each entry is in Microsoft .INI form:
  # [process-pattern]
  # trigger = perl-expression
  # action  = program-and-arguments-to-run

  [httpd$]
    trigger = $count < 4
    action  = echo "$trigger fired -- You have $count httpd sessions."

  [.]
  trigger = $vsz > 10
  action  = echo "Looks like you have a big $command program: $vsz KB"

  # Unfortunately we have use a different pattern below. (Here we use
  # ".?" instead of ".".) In effect the the two patterns mean
  # test every process.
  [.?]
    trigger = elapsed2secs('$etime') > 2*MINS && $pcpu > 40
    occurs  = every
    action  = <<EOT
     echo "$command used $pcpu% CPU for the last $etime seconds" | /bin/mail root
     kill -TERM $pid
  EOT

  # Scripts don't show as the script name as the command name on some
  # operating systems.  Rather the name of the interpreter is listed
  # (e.g. bash or perl) Here's how you can match against a script.
  # BSD/OS is an exception: it does give the script name rather than
  # the interpreter name.
  [/usr/bin/perl]
    trigger = \$args !~ /ps-watcher/
    occurs  = every
    action  = echo "***found perl program ${pid}:\n $args"

=head1 Using $PROLOG for getting non-ps information

Here is an example to show how to use ps-watcher to do something not
really possible from ps: check to see if a I<port> is active.  We make
use of lsof to check port 3333 and the $PROLOG make sure it runs.

  [$PROLOG]
    occurs  = first
    trigger = { \$x=`lsof -i :3333 >/dev/null 2>&1`; \$? >> 8 }
    action  = <<EOT
    put-your-favorite-command-here arg1 arg2 ...
  EOT

=head1 SECURITY CONSIDERATIONS

Any daemon such as this one which is sufficiently flexible is a
security risk. The configuration file allows arbitrary commands to be
run. In particular if this daemon is run as root and the configuration
file is not protected so that it can't be modified, a bad person could
have their programs run as root.

There's nothing in the ps command or ps-watcher, that requires one to
run this daemon as root. 

So as with all daemons, one needs to take usual security precautions
that a careful sysadmin/maintainer of a computer would. If you can run
any daemon as an unprivileged user (or with no privileges), do it!  If
not, set the permissions on the configuration file and the directory
it lives in. 

This program can also run chrooted and there is a C<--path> option
that is available which can be used to set the executable search path.
All commands used by @PACKAGE@ are fully qualified, and I generally
give a full execution path in my configuration file, so consider using
the option C<--path=''>.

Commands that need to be run as root you can run via C<sudo>.  I often
run process accounting which tracks all commands run. Tripwire may be
useful to track changed configuration files.

=head1 TROUBLESHOOTING

To debug a configuration file the following options are useful:

   @PACKAGE@ --log --nodaemon --sleep -1 --debug 2 *config-file*

For even more information and control try running the above under the
perl debugger, e.g.

   perl -d @PACKAGE@ --log --nodaemon --sleep -1 --debug 2 *config-file*

=head1 BUGS

Well, some of these are not so much a bug in @PACKAGE@ so much as a
challenge to getting @PACKAGE@ to do what you want it to do. 

One common problem people run in into is understanding exactly what
the process variables mean. The manual page L<ps(1)> should be of
help, but I've found some of the descriptions either a bit vague or
just plain lacking.

Sometimes one will see this error message when debug tracing is turned on:

  ** debug ** Something wrong getting ps variables

This just means that the process died between the time @PACKAGE@ first
saw the existence of the process and the time that it queried
variables.

=head1 SEE ALSO

See also L<ps(1)> and L<syslogd(8)>.

Another cool program doing ps-like things is C<xps>. Well okay, it's
another program I distributed. It shows the process tree dynamically
updated using X Motif and tries to display the output "attractively"
but fast. You can the find the homepage at
L<http://motif-pstree.sourceforge.net> and it download via
L<http://prdownloads.sourceforge.net/motif-pstree?sort_by=date&sort=desc>

=head1 AUTHOR

Rocky Bernstein (rocky@gnu.org)

=head1 COPYRIGHT

  Copyright (C) 2000, 2002, 2003, 2004, 2005, 2006, 2008
  Rocky Bernstein, email: rocky@gnu.org.
  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., 675 Mass Ave, Cambridge, MA 02139, USA.