perl5.001 patch.1f

[p5sagit/p5-mst-13.2.git] / pod / modpods / Getopt.pod

=head1 NAME

getopt - Process single-character switches with switch clustering

getopts - Process single-character switches with switch clustering

GetOptions - extended getopt processing

=head1 SYNOPSIS

    use Getopt::Std;
    getopt('oDI');  # -o, -D & -I take arg.  Sets opt_* as a side effect.
    getopts('oif:');  # -o & -i are boolean flags, -f takes an argument
		      # Sets opt_* as a side effect.

    use Getopt::Long;
    $result = GetOptions (...option-descriptions...);

=head1 DESCRIPTION

The getopt() functions processes single-character switches with switch
clustering.  Pass one argument which is a string containing all switches
that take an argument.  For each switch found, sets $opt_x (where x is the
switch name) to the value of the argument, or 1 if no argument.  Switches
which take an argument don't care whether there is a space between the
switch and the argument.

The Getopt::Long module implements an extended getopt function called
GetOptions(). This function adheres to the new syntax (long option names,
no bundling).  It tries to implement the better functionality of
traditional, GNU and POSIX getopt() functions.

Each description should designate a valid Perl identifier, optionally
followed by an argument specifier.

Values for argument specifiers are:

  <none>   option does not take an argument
  !        option does not take an argument and may be negated
  =s :s    option takes a mandatory (=) or optional (:) string argument
  =i :i    option takes a mandatory (=) or optional (:) integer argument
  =f :f    option takes a mandatory (=) or optional (:) real number argument

If option "name" is set, it will cause the Perl variable $opt_name to
be set to the specified value. The calling program can use this
variable to detect whether the option has been set. Options that do
not take an argument will be set to 1 (one).

Options that take an optional argument will be defined, but set to ''
if no actual argument has been supplied.

If an "@" sign is appended to the argument specifier, the option is
treated as an array.  Value(s) are not set, but pushed into array
@opt_name.

Options that do not take a value may have an "!" argument specifier to
indicate that they may be negated. E.g. "foo!" will allow B<-foo> (which
sets $opt_foo to 1) and B<-nofoo> (which will set $opt_foo to 0).

The option name may actually be a list of option names, separated by
'|'s, e.g. B<"foo|bar|blech=s". In this example, options 'bar' and
'blech' will set $opt_foo instead.

Option names may be abbreviated to uniqueness, depending on
configuration variable $autoabbrev.

Dashes in option names are allowed (e.g. pcc-struct-return) and will
be translated to underscores in the corresponding Perl variable (e.g.
$opt_pcc_struct_return).  Note that a lone dash "-" is considered an
option, corresponding Perl identifier is $opt_ .

A double dash "--" signals end of the options list.

If the first option of the list consists of non-alphanumeric
characters only, it is interpreted as a generic option starter.
Everything starting with one of the characters from the starter will
be considered an option.

The default values for the option starters are "-" (traditional), "--"
(POSIX) and "+" (GNU, being phased out).

Options that start with "--" may have an argument appended, separated
with an "=", e.g. "--foo=bar".

If configuration variable $getopt_compat is set to a non-zero value,
options that start with "+" may also include their arguments,
e.g. "+foo=bar".

A return status of 0 (false) indicates that the function detected
one or more errors.

=head1 EXAMPLES

If option "one:i" (i.e. takes an optional integer argument), then
the following situations are handled:

   -one -two		-> $opt_one = '', -two is next option
   -one -2		-> $opt_one = -2

Also, assume "foo=s" and "bar:s" :

   -bar -xxx		-> $opt_bar = '', '-xxx' is next option
   -foo -bar		-> $opt_foo = '-bar'
   -foo --		-> $opt_foo = '--'

In GNU or POSIX format, option names and values can be combined:

   +foo=blech		-> $opt_foo = 'blech'
   --bar=		-> $opt_bar = ''
   --bar=--		-> $opt_bar = '--'

=over 12

=item $autoabbrev      

Allow option names to be abbreviated to uniqueness.
Default is 1 unless environment variable
POSIXLY_CORRECT has been set.

=item $getopt_compat   

Allow '+' to start options.
Default is 1 unless environment variable
POSIXLY_CORRECT has been set.

=item $option_start    

Regexp with option starters.
Default is (--|-) if environment variable
POSIXLY_CORRECT has been set, (--|-|\+) otherwise.

=item $order           

Whether non-options are allowed to be mixed with
options.
Default is $REQUIRE_ORDER if environment variable
POSIXLY_CORRECT has been set, $PERMUTE otherwise.

=item $ignorecase      

Ignore case when matching options. Default is 1.

=item $debug           

Enable debugging output. Default is 0.

=back

=head1 NOTE

Does not yet use the Exporter--or even packages!!
Thus, it's not a real module.