Getopt_Long
GetOptions - extended processing of command line options
<![CDATA[
use Getopt::Long;
$result = GetOptions (...option-descriptions...);
]]>
The Getopt::Long module implements an extended getopt function called
GetOptions(). This function adheres to the POSIX syntax for command
line options, with GNU extensions. In general, this means that options
have long names instead of single letters, and are introduced with a
double dash ``--''. There is no bundling of command line options, as was
the case with the more traditional single-letter approach. For
example, the UNIX ``ps'' command can be given the command line ``option''
<![CDATA[
-vax
]]>
which means the combination of
-v
,
-a
and
-x
. With the new
syntax --vax would be a single option, probably indicating a
computer architecture.
Command line options can be used to set values. These values can be
specified in one of two ways:
<![CDATA[
--size 24
--size=24
]]>
GetOptions is called with a list of option-descriptions, each of which
consists of two elements: the option specifier and the option linkage.
The option specifier defines the name of the option and, optionally,
the value it can take. The option linkage is usually a reference to a
variable that will be set when the option is used. For example, the
following call to GetOptions:
<![CDATA[
&GetOptions("size=i" => \$offset);
]]>
will accept a command line option ``size'' that must have an integer
value. With a command line of ``--size 24'' this will cause the variable
$offset to get the value 24.
Alternatively, the first argument to GetOptions may be a reference to
a HASH describing the linkage for the options. The following call is
equivalent to the example above:
<![CDATA[
%optctl = ("size" => \$offset);
&GetOptions(\%optctl, "size=i");
]]>
Linkage may be specified using either of the above methods, or both.
Linkage specified in the argument list takes precedence over the
linkage specified in the HASH.
The command line options are taken from array
@ARGV
. Upon completion
of GetOptions,
@ARGV
will contain the rest (i.e. the non-options) of
the command line.
Each option specifier designates the name of the option, optionally
followed by an argument specifier. Values for argument specifiers are:
-
-
Option does not take an argument.
The option variable will be set to 1.
-
!
-
Option does not take an argument and may be negated, i.e. prefixed by
``no''. E.g. ``foo!'' will allow --foo (with value 1) and -nofoo
(with value 0).
The option variable will be set to 1, or 0 if negated.
-
=s
-
Option takes a mandatory string argument.
This string will be assigned to the option variable.
Note that even if the string argument starts with - or --, it
will not be considered an option on itself.
-
:s
-
Option takes an optional string argument.
This string will be assigned to the option variable.
If omitted, it will be assigned ``'' (an empty string).
If the string argument starts with - or --, it
will be considered an option on itself.
-
=i
-
Option takes a mandatory integer argument.
This value will be assigned to the option variable.
Note that the value may start with - to indicate a negative
value.
-
:i
-
Option takes an optional integer argument.
This value will be assigned to the option variable.
If omitted, the value 0 will be assigned.
Note that the value may start with - to indicate a negative
value.
-
=f
-
Option takes a mandatory real number argument.
This value will be assigned to the option variable.
Note that the value may start with - to indicate a negative
value.
-
:f
-
Option takes an optional real number argument.
This value will be assigned to the option variable.
If omitted, the value 0 will be assigned.
A lone dash - is considered an option, the corresponding optionname is the empty string.
A double dash on itself -- signals end of the options list.
The linkage specifier is optional. If no linkage is explicitly
specified but a ref HASH is passed, GetOptions will place the value in
the HASH. For example:
<![CDATA[
%optctl = ();
&GetOptions (\%optctl, "size=i");
]]>
will perform the equivalent of the assignment
<![CDATA[
$optctl{"size"} = 24;
]]>
For array options, a reference to an array is used, e.g.:
<![CDATA[
%optctl = ();
&GetOptions (\%optctl, "sizes=i@");
]]>
with command line ``-sizes 24 -sizes 48'' will perform the equivalent of
the assignment
<![CDATA[
$optctl{"sizes"} = [24, 48];
]]>
If no linkage is explicitly specified and no ref HASH is passed,
GetOptions will put the value in a global variable named after the
option, prefixed by ``opt_''. To yield a usable Perl variable,
characters that are not part of the syntax for variables are
translated to underscores. For example, ``--fpp-struct-return'' will set
the variable $opt_fpp_struct_return. Note that this variable resides
in the namespace of the calling program, not necessarily main.
For example:
<![CDATA[
&GetOptions ("size=i", "sizes=i@");
]]>
with command line ``-size 10 -sizes 24 -sizes 48'' will perform the
equivalent of the assignments
<![CDATA[
$opt_size = 10;
@opt_sizes = (24, 48);
]]>
A lone dash - is considered an option, the corresponding Perl
identifier is $opt_ .
The linkage specifier can be a reference to a scalar, a reference to
an array or a reference to a subroutine.
If a REF SCALAR is supplied, the new value is stored in the referenced
variable. If the option occurs more than once, the previous value is
overwritten.
If a REF ARRAY is supplied, the new value is appended (pushed) to the
referenced array.
If a REF CODE is supplied, the referenced subroutine is called with
two arguments: the option name and the option value.
The option name is always the true name, not an abbreviation or alias.
The option name may actually be a list of option names, separated by
``|''s, e.g. ``foo|bar|blech=s''. In this example, ``foo'' is the true name
op this option. If no linkage is specified, options ``foo'', ``bar'' and
``blech'' all will set $opt_foo.
Option names may be abbreviated to uniqueness, depending on
configuration variable
$Getopt::Long::autoabbrev
.
A special option specifier, <>, can be used to designate a subroutine
to handle non-option arguments. GetOptions will immediately call this
subroutine for every non-option it encounters in the options list.
This subroutine gets the name of the non-option passed.
This feature requires
$Getopt::Long::order
to have the value $PERMUTE.
See also the examples.
On the command line, options can start with - (traditional), --
(POSIX) and + (GNU, now being phased out). The latter is not
allowed if the environment variable POSIXLY_CORRECT has been
defined.
Options that start with ``--'' may have an argument appended, separated
with an ``='', e.g. ``--foo=bar''.
A return status of 0 (false) indicates that the function detected
one or more errors.
Getopt::Long::GetOptions() is the successor of
newgetopt.pl that came with Perl 4. It is fully upward compatible.
In fact, the Perl 5 version of newgetopt.pl is just a wrapper around
the module.
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. This only applies if no linkage is supplied.
If configuration variable
$Getopt::Long::getopt_compat
is set to a
non-zero value, options that start with ``+'' may also include their
arguments, e.g. ``+foo=bar''. This is for compatiblity with older
implementations of the GNU ``getopt'' routine.
If the first argument to GetOptions is a string consisting of only
non-alphanumeric characters, it is taken to specify the option starter
characters. Everything starting with one of these characters from the
starter will be considered an option. BFor convenience, option specifiers may have a leading - or --,
so it is possible to write:
<![CDATA[
GetOptions qw(-foo=s --bar=i --ar=s);
]]>
If the option specifier is ``one:i'' (i.e. takes an optional integer
argument), then the following situations are handled:
<![CDATA[
-one -two -> $opt_one = '', -two is next option
-one -2 -> $opt_one = -2
]]>
Also, assume specifiers ``foo=s'' and ``bar:s'' :
<![CDATA[
-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:
<![CDATA[
+foo=blech -> $opt_foo = 'blech'
--bar= -> $opt_bar = ''
--bar=-- -> $opt_bar = '--'
]]>
Example of using variabel references:
<![CDATA[
$ret = &GetOptions ('foo=s', \$foo, 'bar=i', 'ar=s', \@ar);
]]>
With command line options ``-foo blech -bar 24 -ar xx -ar yy''
this will result in:
<![CDATA[
$bar = 'blech'
$opt_bar = 24
@ar = ('xx','yy')
]]>
Example of using the <> option specifier:
<![CDATA[
@ARGV = qw(-foo 1 bar -foo 2 blech);
&GetOptions("foo=i", \$myfoo, "<>", \&mysub);
]]>
Results:
<![CDATA[
&mysub("bar") will be called (with $myfoo being 1)
&mysub("blech") will be called (with $myfoo being 2)
]]>
Compare this with:
<![CDATA[
@ARGV = qw(-foo 1 bar -foo 2 blech);
&GetOptions("foo=i", \$myfoo);
]]>
This will leave the non-options in @ARGV:
<![CDATA[
$myfoo -> 2
@ARGV -> qw(bar blech)
]]>
The following variables can be set to change the default behaviour of
GetOptions():
-
$Getopt::Long::autoabbrev
-
Allow option names to be abbreviated to uniqueness.
Default is 1 unless environment variable
POSIXLY_CORRECT has been set.
-
$Getopt::Long::getopt_compat
-
Allow '+' to start options.
Default is 1 unless environment variable
POSIXLY_CORRECT has been set.
-
$Getopt::Long::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.
$PERMUTE means that
<![CDATA[
-foo arg1 -bar arg2 arg3
]]>
is equivalent to
<![CDATA[
-foo -bar arg1 arg2 arg3
]]>
If a non-option call-back routine is specified,
@ARGV
will always be
empty upon succesful return of GetOptions since all options have been
processed, except when -- is used:
<![CDATA[
-foo arg1 -bar arg2 -- arg3
]]>
will call the call-back routine for arg1 and arg2, and terminate
leaving arg2 in
@ARGV
.
If
$Getopt::Long::order
is $REQUIRE_ORDER, options processing
terminates when the first non-option is encountered.
<![CDATA[
-foo arg1 -bar arg2 arg3
]]>
is equivalent to
<![CDATA[
-foo -- arg1 -bar arg2 arg3
]]>
$RETURN_IN_ORDER is not supported by GetOptions().
-
$Getopt::Long::ignorecase
-
Ignore case when matching options. Default is 1.
-
$Getopt::Long::VERSION
-
The version number of this Getopt::Long implementation in the format
major.minor. This can be used to have Exporter check the
version, e.g.
<![CDATA[
use Getopt::Long 2.00;
]]>
You can inspect $Getopt::Long::major_version and
$Getopt::Long::minor_version for the individual components.
-
$Getopt::Long::error
-
Internal error flag. May be incremented from a call-back routine to
cause options parsing to fail.
-
$Getopt::Long::debug
-
Enable copious debugging output. Default is 0.