CONSTRUCTOR¶

  # Instantiate object (usage is mandatory)
  $ng = Nagios::Plugin::Getopt->new(
    usage => 'Usage: %s --hello',
    version => '0.01',
  );

The Nagios::Plugin::Getopt constructor accepts the following named arguments:

usage (required)

Short usage message used with --usage/-? and with missing required arguments, and included in the longer --help output. Can include a '%s' sprintf placeholder which will be replaced with the plugin name e.g.

  usage => qq(Usage: %s -H <hostname> -p <ports> [-v]),
    

might be displayed as:

  $ ./check_tcp_range --usage
  Usage: check_tcp_range -H <hostname> -p <ports> [-v]
    

version (required)

Plugin version number, included in the --version/-V output, and in the longer --help output. e.g.

  $ ./check_tcp_range --version
  check_tcp_range 0.2 [http://www.openfusion.com.au/labs/nagios/]
    

url

URL for info about this plugin, included in the --version/-V output, and in the longer --help output (see preceding 'version' example).

blurb

Short plugin description, included in the longer --help output (see below for an example).

license

License text, included in the longer --help output (see below for an example). By default, this is set to the standard nagios plugins GPL license text:

  This nagios plugin is free software, and comes with ABSOLUTELY 
  NO WARRANTY. It may be used, redistributed and/or modified under 
  the terms of the GNU General Public Licence (see 
  http://www.fsf.org/licensing/licenses/gpl.txt).
    

Provide your own to replace this text in the help output.

extra

Extra text to be appended at the end of the longer --help output.

plugin

Plugin name. This defaults to the basename of your plugin, which is usually correct, but you can set it explicitly if not.

timeout

Timeout period in seconds, overriding the standard timeout default (15 seconds).

The full --help output has the following form:

  version string
  license string
  blurb
  usage string
  options list
  extra text

The 'blurb' and 'extra text' sections are omitted if not supplied. For example:

  $ ./check_tcp_range -h
  check_tcp_range 0.2 [http://www.openfusion.com.au/labs/nagios/]
  This nagios plugin is free software, and comes with ABSOLUTELY NO WARRANTY. 
  It may be used, redistributed and/or modified under the terms of the GNU 
  General Public Licence (see http://www.fsf.org/licensing/licenses/gpl.txt).
  This plugin tests arbitrary ranges/sets of tcp ports for a host.
  Usage: check_tcp_range -H <hostname> -p <ports> [-v]
  Options:
   -h, --help
     Print detailed help screen
   -V, --version
     Print version information
   -H, --hostname=ADDRESS
     Host name or IP address
   -p, --ports=STRING
     Port numbers to check. Format: comma-separated, colons for ranges,
     no spaces e.g. 8700:8705,8710:8715,8760 
   -t, --timeout=INTEGER
     Seconds before plugin times out (default: 15)
   -v, --verbose
     Show details for command-line debugging (can repeat up to 3 times)

ARGUMENTS¶

You can define arguments for your plugin using the arg() method, which supports both named and positional arguments. In both cases the "spec" and "help" arguments are required, while the "label", "default", and "required" arguments are optional:

  # Define --hello argument (named parameters)
  $ng->arg(
    spec => 'hello|h=s', 
    help => "Hello string",
    required => 1,
  );
  # Define --hello argument (positional parameters)
  #   Parameter order is 'spec', 'help', 'default', 'required?', 'label'
  $ng->arg('hello|h=s', "Hello parameter (default %s)", 5, 1);

spec

The "spec" argument (the first argument in the positional variant) is a Getopt::Long argument specification. See Getopt::Long for the details, but basically it is a series of one or more argument names for this argument (separated by '|'), suffixed with an '=<type>' indicator if the argument takes a value. '=s' indicates a string argument; '=i' indicates an integer argument; appending an '@' indicates multiple such arguments are accepted; and so on. The following are some examples:

help

The "help" argument is a string displayed in the --help option list output, or it can be a list (an arrayref) of such strings, for multi-line help (see below).

The help string is munged in two ways:

  $ng->arg(
    spec => 'warning|w=s',
    help => [
      'Exit with WARNING status if less than BYTES bytes of disk are free',
      'Exit with WARNING status if less than PERCENT of disk is free',
    ],
    label => [ 'BYTES', 'PERCENT%' ],
  );

 -w, --warning=BYTES
    Exit with WARNING status if less than BYTES bytes of disk are free
 -w, --warning=PERCENT%
    Exit with WARNING status if less than PERCENT of disk space is free

label

The "label" argument is a scalar or an arrayref (see 'Multi-line help' description above) that overrides the standard type expansion when generating help text from the spec definition. By default, "spec=i" arguments are labelled as "=INTEGER" in the help text, and "spec=s" arguments are labelled as "=STRING". By supplying your own "label" argument you can override these standard 'INTEGER' and 'STRING' designations.

For multi-line help, you can supply an ordered list (arrayref) of labels to match the list of help strings e.g.

  label => [ 'BYTES', 'PERCENT%' ]
    

Any labels that are left as undef (or just omitted, if trailing) will just use the default 'INTEGER' or 'STRING' designations e.g.

  label => [ undef, 'PERCENT%' ]
    

default

The "default" argument is the default value to be given to this parameter if none is explicitly supplied.

required

The "required" argument is a boolean used to indicate that this argument is mandatory (Nagios::Plugin::Getopt will exit with your usage message and a 'Missing argument' indicator if any required arguments are not supplied).

Note that --help lists your arguments in the order they are defined, so you should order your arg() calls accordingly.

GETOPTS¶

The main parsing and processing functionality is provided by the getopts() method, which takes no arguments:

  # Parse and process arguments
  $ng->getopts;

This parses the command line arguments passed to your plugin using Getopt::Long and the builtin and provided argument specifications. Flags and argument values are recorded within the object, and can be accessed either using the generic get() accessor, or using named accessors corresponding to your argument names. For example:

  print $ng->get('hello');
  print $ng->hello();
  if ($ng->verbose) {
    # ...
  }
  if ($ng->get('ports') =~ m/:/) {
    # ...
  }

Note that where you have defined alternate argument names, the first is considered the citation form. All the builtin arguments are available using their long variant names.

BUILTIN PROCESSING¶

The getopts() method also handles processing of the immediate builtin arguments, namely --usage, --version, --help, as well as checking all required arguments have been supplied, so you don't have to handle those yourself. This means that your plugin will exit from the getopts() call in these cases - if you want to catch that you can run getopts() within an eval{}.

getopts() also sets up a default ALRM timeout handler so you can use an

  alarm $ng->timeout;

around any blocking operations within your plugin (which you are free to override if you want to use a custom timeout message).