1############################################################################# 2# Pod/Usage.pm -- print usage messages for the running script. 3# 4# Copyright (c) 1996-2000 by Bradford Appleton. All rights reserved. 5# Copyright (c) 2001-2016 by Marek Rouchal. 6# This file is part of "Pod-Usage". Pod-Usage is free software; 7# you can redistribute it and/or modify it under the same terms 8# as Perl itself. 9############################################################################# 10 11package Pod::Usage; 12 13use strict; 14require 5.006; ## requires this Perl version or later 15 16use Carp; 17use Config; 18use Exporter; 19use File::Spec; 20 21our $VERSION = '2.01'; 22 23our @EXPORT = qw(&pod2usage); 24our @ISA; 25BEGIN { 26 $Pod::Usage::Formatter ||= 'Pod::Text'; 27 eval "require $Pod::Usage::Formatter"; 28 die $@ if $@; 29 @ISA = ( $Pod::Usage::Formatter ); 30} 31 32our $MAX_HEADING_LEVEL = 3; 33 34##--------------------------------------------------------------------------- 35 36##--------------------------------- 37## Function definitions begin here 38##--------------------------------- 39 40sub pod2usage { 41 local($_) = shift; 42 my %opts; 43 ## Collect arguments 44 if (@_ > 0) { 45 ## Too many arguments - assume that this is a hash and 46 ## the user forgot to pass a reference to it. 47 %opts = ($_, @_); 48 } 49 elsif (!defined $_) { 50 $_ = ''; 51 } 52 elsif (ref $_) { 53 ## User passed a ref to a hash 54 %opts = %{$_} if (ref($_) eq 'HASH'); 55 } 56 elsif (/^[-+]?\d+$/) { 57 ## User passed in the exit value to use 58 $opts{'-exitval'} = $_; 59 } 60 else { 61 ## User passed in a message to print before issuing usage. 62 $_ and $opts{'-message'} = $_; 63 } 64 65 ## Need this for backward compatibility since we formerly used 66 ## options that were all uppercase words rather than ones that 67 ## looked like Unix command-line options. 68 ## to be uppercase keywords) 69 %opts = map { 70 my ($key, $val) = ($_, $opts{$_}); 71 $key =~ s/^(?=\w)/-/; 72 $key =~ /^-msg/i and $key = '-message'; 73 $key =~ /^-exit/i and $key = '-exitval'; 74 lc($key) => $val; 75 } (keys %opts); 76 77 ## Now determine default -exitval and -verbose values to use 78 if ((! defined $opts{'-exitval'}) && (! defined $opts{'-verbose'})) { 79 $opts{'-exitval'} = 2; 80 $opts{'-verbose'} = 0; 81 } 82 elsif (! defined $opts{'-exitval'}) { 83 $opts{'-exitval'} = ($opts{'-verbose'} > 0) ? 1 : 2; 84 } 85 elsif (! defined $opts{'-verbose'}) { 86 $opts{'-verbose'} = (lc($opts{'-exitval'}) eq 'noexit' || 87 $opts{'-exitval'} < 2); 88 } 89 90 ## Default the output file 91 $opts{'-output'} = (lc($opts{'-exitval'}) eq 'noexit' || 92 $opts{'-exitval'} < 2) ? \*STDOUT : \*STDERR 93 unless (defined $opts{'-output'}); 94 ## Default the input file 95 $opts{'-input'} = $0 unless (defined $opts{'-input'}); 96 97 ## Look up input file in path if it doesn't exist. 98 unless ((ref $opts{'-input'}) || (-e $opts{'-input'})) { 99 my $basename = $opts{'-input'}; 100 my $pathsep = ($^O =~ /^(?:dos|os2|MSWin32)$/i) ? ';' 101 : (($^O eq 'MacOS' || $^O eq 'VMS') ? ',' : ':'); 102 my $pathspec = $opts{'-pathlist'} || $ENV{PATH} || $ENV{PERL5LIB}; 103 104 my @paths = (ref $pathspec) ? @$pathspec : split($pathsep, $pathspec); 105 for my $dirname (@paths) { 106 $_ = length($dirname) ? File::Spec->catfile($dirname, $basename) : $basename; 107 last if (-e $_) && ($opts{'-input'} = $_); 108 } 109 } 110 111 ## Now create a pod reader and constrain it to the desired sections. 112 my $parser = Pod::Usage->new(USAGE_OPTIONS => \%opts); 113 if ($opts{'-verbose'} == 0) { 114 $parser->select('(?:SYNOPSIS|USAGE)\s*'); 115 } 116 elsif ($opts{'-verbose'} == 1) { 117 my $opt_re = '(?i)' . 118 '(?:OPTIONS|ARGUMENTS)' . 119 '(?:\s*(?:AND|\/)\s*(?:OPTIONS|ARGUMENTS))?'; 120 $parser->select( '(?:SYNOPSIS|USAGE)\s*', $opt_re, "DESCRIPTION/$opt_re" ); 121 } 122 elsif ($opts{'-verbose'} >= 2 && $opts{'-verbose'} != 99) { 123 $parser->select('.*'); 124 } 125 elsif ($opts{'-verbose'} == 99) { 126 my $sections = $opts{'-sections'}; 127 $parser->select( (ref $sections) ? @$sections : $sections ); 128 $opts{'-verbose'} = 1; 129 } 130 131 ## Check for perldoc 132 my $progpath = $opts{'-perldoc'} ? $opts{'-perldoc'} : 133 File::Spec->catfile($Config{scriptdirexp} || $Config{scriptdir}, 134 'perldoc'); 135 136 my $version = sprintf("%vd",$^V); 137 if ($Config{versiononly} and $Config{startperl} =~ /\Q$version\E$/ ) { 138 $progpath .= $version; 139 } 140 $opts{'-noperldoc'} = 1 unless -e $progpath; 141 142 ## Now translate the pod document and then exit with the desired status 143 if ( !$opts{'-noperldoc'} 144 and $opts{'-verbose'} >= 2 145 and !ref($opts{'-input'}) 146 and $opts{'-output'} == \*STDOUT ) 147 { 148 ## spit out the entire PODs. Might as well invoke perldoc 149 print { $opts{'-output'} } ($opts{'-message'}, "\n") if($opts{'-message'}); 150 if(defined $opts{-input} && $opts{-input} =~ /^\s*(\S.*?)\s*$/) { 151 # the perldocs back to 5.005 should all have -F 152 # without -F there are warnings in -T scripts 153 my $f = $1; 154 my @perldoc_cmd = ($progpath); 155 if ($opts{'-perldocopt'}) { 156 $opts{'-perldocopt'} =~ s/^\s+|\s+$//g; 157 push @perldoc_cmd, split(/\s+/, $opts{'-perldocopt'}); 158 } 159 push @perldoc_cmd, ('-F', $f); 160 unshift @perldoc_cmd, $opts{'-perlcmd'} if $opts{'-perlcmd'}; 161 system(@perldoc_cmd); 162 # RT16091: fall back to more if perldoc failed 163 if($?) { 164 # RT131844: prefer PAGER env 165 my $pager = $ENV{PAGER} || $Config{pager}; 166 if(defined($pager) && length($pager)) { 167 my $cmd = $pager . ' ' . ($^O =~ /win/i ? qq("$f") : quotemeta($f)); 168 system($cmd); 169 } else { 170 # the most humble fallback; should work (at least) on *nix and Win 171 system('more', $f); 172 } 173 } 174 } else { 175 croak "Unspecified input file or insecure argument.\n"; 176 } 177 } 178 else { 179 $parser->parse_from_file($opts{'-input'}, $opts{'-output'}); 180 } 181 182 exit($opts{'-exitval'}) unless (lc($opts{'-exitval'}) eq 'noexit'); 183} 184 185##--------------------------------------------------------------------------- 186 187##------------------------------- 188## Method definitions begin here 189##------------------------------- 190 191sub new { 192 my $this = shift; 193 my $class = ref($this) || $this; 194 my %params = @_; 195 my $self = {%params}; 196 bless $self, $class; 197 if ($self->can('initialize')) { 198 $self->initialize(); 199 } else { 200 # pass through options to Pod::Text 201 my %opts; 202 for (qw(alt code indent loose margin quotes sentence stderr utf8 width)) { 203 my $val = $params{USAGE_OPTIONS}{"-$_"}; 204 $opts{$_} = $val if defined $val; 205 } 206 $self = $self->SUPER::new(%opts); 207 %$self = (%$self, %params); 208 } 209 return $self; 210} 211 212# This subroutine was copied in whole-cloth from Pod::Select 1.60 in order to 213# allow the ejection of Pod::Select from the core without breaking Pod::Usage. 214# -- rjbs, 2013-03-18 215sub _compile_section_spec { 216 my ($section_spec) = @_; 217 my (@regexs, $negated); 218 219 ## Compile the spec into a list of regexs 220 local $_ = $section_spec; 221 s{\\\\}{\001}g; ## handle escaped backward slashes 222 s{\\/}{\002}g; ## handle escaped forward slashes 223 224 ## Parse the regexs for the heading titles 225 @regexs = split(/\//, $_, $MAX_HEADING_LEVEL); 226 227 ## Set default regex for ommitted levels 228 for (my $i = 0; $i < $MAX_HEADING_LEVEL; ++$i) { 229 $regexs[$i] = '.*' unless ((defined $regexs[$i]) 230 && (length $regexs[$i])); 231 } 232 ## Modify the regexs as needed and validate their syntax 233 my $bad_regexs = 0; 234 for (@regexs) { 235 $_ .= '.+' if ($_ eq '!'); 236 s{\001}{\\\\}g; ## restore escaped backward slashes 237 s{\002}{\\/}g; ## restore escaped forward slashes 238 $negated = s/^\!//; ## check for negation 239 eval "m{$_}"; ## check regex syntax 240 if ($@) { 241 ++$bad_regexs; 242 carp qq{Bad regular expression /$_/ in "$section_spec": $@\n}; 243 } 244 else { 245 ## Add the forward and rear anchors (and put the negator back) 246 $_ = '^' . $_ unless (/^\^/); 247 $_ = $_ . '$' unless (/\$$/); 248 $_ = '!' . $_ if ($negated); 249 } 250 } 251 return (! $bad_regexs) ? [ @regexs ] : undef; 252} 253 254sub select { 255 my ($self, @sections) = @_; 256 if ($ISA[0]->can('select')) { 257 $self->SUPER::select(@sections); 258 } else { 259 # we're using Pod::Simple - need to mimic the behavior of Pod::Select 260 my $add = ($sections[0] eq '+') ? shift(@sections) : ''; 261 ## Reset the set of sections to use 262 unless (@sections) { 263 delete $self->{USAGE_SELECT} unless ($add); 264 return; 265 } 266 $self->{USAGE_SELECT} = [] 267 unless ($add && $self->{USAGE_SELECT}); 268 my $sref = $self->{USAGE_SELECT}; 269 ## Compile each spec 270 for my $spec (@sections) { 271 my $cs = _compile_section_spec($spec); 272 if ( defined $cs ) { 273 ## Store them in our sections array 274 push(@$sref, $cs); 275 } else { 276 carp qq{Ignoring section spec "$spec"!\n}; 277 } 278 } 279 } 280} 281 282# Override Pod::Text->seq_i to return just "arg", not "*arg*". 283sub seq_i { return $_[1] } 284# Override Pod::Text->cmd_i to return just "arg", not "*arg*". 285# newer version based on Pod::Simple 286sub cmd_i { 287 my $self = shift; 288 # RT121489: highlighting should be there with Termcap 289 return $self->SUPER::cmd_i(@_) if $self->isa('Pod::Text::Termcap'); 290 return $_[1]; 291} 292 293# This overrides the Pod::Text method to do something very akin to what 294# Pod::Select did as well as the work done below by preprocess_paragraph. 295# Note that the below is very, very specific to Pod::Text and Pod::Simple. 296sub _handle_element_end { 297 my ($self, $element) = @_; 298 if ($element eq 'head1') { 299 $self->{USAGE_HEADINGS} = [ $$self{PENDING}[-1][1] ]; 300 if ($self->{USAGE_OPTIONS}->{-verbose} < 2) { 301 $$self{PENDING}[-1][1] =~ s/^\s*SYNOPSIS\s*$/USAGE/; 302 } 303 } elsif ($element =~ /^head(\d+)$/ && $1) { # avoid 0 304 my $idx = $1 - 1; 305 $self->{USAGE_HEADINGS} = [] unless($self->{USAGE_HEADINGS}); 306 $self->{USAGE_HEADINGS}->[$idx] = $$self{PENDING}[-1][1]; 307 # we have to get rid of the lower headings 308 splice(@{$self->{USAGE_HEADINGS}},$idx+1); 309 } 310 if ($element =~ /^head\d+$/) { 311 $$self{USAGE_SKIPPING} = 1; 312 if (!$$self{USAGE_SELECT} || !@{ $$self{USAGE_SELECT} }) { 313 $$self{USAGE_SKIPPING} = 0; 314 } else { 315 my @headings = @{$$self{USAGE_HEADINGS}}; 316 for my $section_spec ( @{$$self{USAGE_SELECT}} ) { 317 my $match = 1; 318 for (my $i = 0; $i < $MAX_HEADING_LEVEL; ++$i) { 319 $headings[$i] = '' unless defined $headings[$i]; 320 my $regex = $section_spec->[$i]; 321 my $negated = ($regex =~ s/^\!//); 322 $match &= ($negated ? ($headings[$i] !~ /${regex}/) 323 : ($headings[$i] =~ /${regex}/)); 324 last unless ($match); 325 } # end heading levels 326 if ($match) { 327 $$self{USAGE_SKIPPING} = 0; 328 last; 329 } 330 } # end sections 331 } 332 333 # Try to do some lowercasing instead of all-caps in headings, and use 334 # a colon to end all headings. 335 if($self->{USAGE_OPTIONS}->{-verbose} < 2) { 336 local $_ = $$self{PENDING}[-1][1]; 337 s{([A-Z])([A-Z]+)}{((length($2) > 2) ? $1 : lc($1)) . lc($2)}ge; 338 s/\s*$/:/ unless (/:\s*$/); 339 $_ .= "\n"; 340 $$self{PENDING}[-1][1] = $_; 341 } 342 } 343 if ($$self{USAGE_SKIPPING} && $element !~ m/^over-|^[BCFILSZ]$/) { 344 pop @{ $$self{PENDING} }; 345 } else { 346 $self->SUPER::_handle_element_end($element); 347 } 348} 349 350# required for Pod::Simple API 351sub start_document { 352 my $self = shift; 353 $self->SUPER::start_document(); 354 my $msg = $self->{USAGE_OPTIONS}->{-message} or return 1; 355 my $out_fh = $self->output_fh(); 356 print $out_fh "$msg\n"; 357} 358 359# required for old Pod::Parser API 360sub begin_pod { 361 my $self = shift; 362 $self->SUPER::begin_pod(); ## Have to call superclass 363 my $msg = $self->{USAGE_OPTIONS}->{-message} or return 1; 364 my $out_fh = $self->output_handle(); 365 print $out_fh "$msg\n"; 366} 367 368sub preprocess_paragraph { 369 my $self = shift; 370 local $_ = shift; 371 my $line = shift; 372 ## See if this is a heading and we aren't printing the entire manpage. 373 if (($self->{USAGE_OPTIONS}->{-verbose} < 2) && /^=head/) { 374 ## Change the title of the SYNOPSIS section to USAGE 375 s/^=head1\s+SYNOPSIS\s*$/=head1 USAGE/; 376 ## Try to do some lowercasing instead of all-caps in headings 377 s{([A-Z])([A-Z]+)}{((length($2) > 2) ? $1 : lc($1)) . lc($2)}ge; 378 ## Use a colon to end all headings 379 s/\s*$/:/ unless (/:\s*$/); 380 $_ .= "\n"; 381 } 382 return $self->SUPER::preprocess_paragraph($_); 383} 384 3851; # keep require happy 386 387__END__ 388 389=for stopwords pod2usage verboseness downcased MSWin32 Marek Rouchal Christiansen ATOOMIC rjbs McDougall 390 391=head1 NAME 392 393Pod::Usage - extracts POD documentation and shows usage information 394 395=head1 SYNOPSIS 396 397 use Pod::Usage; 398 399 my $message_text = "This text precedes the usage message."; 400 my $exit_status = 2; ## The exit status to use 401 my $verbose_level = 0; ## The verbose level to use 402 my $filehandle = \*STDERR; ## The filehandle to write to 403 404 pod2usage($message_text); 405 406 pod2usage($exit_status); 407 408 pod2usage( { -message => $message_text , 409 -exitval => $exit_status , 410 -verbose => $verbose_level, 411 -output => $filehandle } ); 412 413 pod2usage( -msg => $message_text , 414 -exitval => $exit_status , 415 -verbose => $verbose_level, 416 -output => $filehandle ); 417 418 pod2usage( -verbose => 2, 419 -noperldoc => 1 ); 420 421 pod2usage( -verbose => 2, 422 -perlcmd => $path_to_perl, 423 -perldoc => $path_to_perldoc, 424 -perldocopt => $perldoc_options ); 425 426=head1 ARGUMENTS 427 428B<pod2usage> should be given either a single argument, or a list of 429arguments corresponding to an associative array (a "hash"). When a single 430argument is given, it should correspond to exactly one of the following: 431 432=over 4 433 434=item * 435 436A string containing the text of a message to print I<before> printing 437the usage message 438 439=item * 440 441A numeric value corresponding to the desired exit status 442 443=item * 444 445A reference to a hash 446 447=back 448 449If more than one argument is given then the entire argument list is 450assumed to be a hash. If a hash is supplied (either as a reference or 451as a list) it should contain one or more elements with the following 452keys: 453 454=over 4 455 456=item C<-message> I<string> 457 458=item C<-msg> I<string> 459 460The text of a message to print immediately prior to printing the 461program's usage message. 462 463=item C<-exitval> I<value> 464 465The desired exit status to pass to the B<exit()> function. 466This should be an integer, or else the string C<NOEXIT> to 467indicate that control should simply be returned without 468terminating the invoking process. 469 470=item C<-verbose> I<value> 471 472The desired level of "verboseness" to use when printing the usage message. 473If the value is 0, then only the "SYNOPSIS" and/or "USAGE" sections of the 474pod documentation are printed. If the value is 1, then the "SYNOPSIS" and/or 475"USAGE" sections, along with any section entitled "OPTIONS", "ARGUMENTS", or 476"OPTIONS AND ARGUMENTS" is printed. If the corresponding value is 2 or more 477then the entire manpage is printed, using L<perldoc> if available; otherwise 478L<Pod::Text> is used for the formatting. For better readability, the 479all-capital headings are downcased, e.g. C<SYNOPSIS> =E<gt> C<Synopsis>. 480 481The special verbosity level 99 requires to also specify the -sections 482parameter; then these sections are extracted and printed. 483 484=item C<-sections> I<spec> 485 486There are two ways to specify the selection. Either a string (scalar) 487representing a selection regexp for sections to be printed when -verbose 488is set to 99, e.g. 489 490 "NAME|SYNOPSIS|DESCRIPTION|VERSION" 491 492With the above regexp all content following (and including) any of the 493given C<=head1> headings will be shown. It is possible to restrict the 494output to particular subsections only, e.g.: 495 496 "DESCRIPTION/Algorithm" 497 498This will output only the C<=head2 Algorithm> heading and content within 499the C<=head1 DESCRIPTION> section. The regexp binding is stronger than the 500section separator, such that e.g.: 501 502 "DESCRIPTION|OPTIONS|ENVIRONMENT/Caveats" 503 504will print any C<=head2 Caveats> section (only) within any of the three 505C<=head1> sections. 506 507Alternatively, an array reference of section specifications can be used: 508 509 pod2usage(-verbose => 99, -sections => [ 510 qw(DESCRIPTION DESCRIPTION/Introduction) ] ); 511 512This will print only the content of C<=head1 DESCRIPTION> and the 513C<=head2 Introduction> sections, but no other C<=head2>, and no other 514C<=head1> either. 515 516=item C<-output> I<handle> 517 518A reference to a filehandle, or the pathname of a file to which the 519usage message should be written. The default is C<\*STDERR> unless the 520exit value is less than 2 (in which case the default is C<\*STDOUT>). 521 522=item C<-input> I<handle> 523 524A reference to a filehandle, or the pathname of a file from which the 525invoking script's pod documentation should be read. It defaults to the 526file indicated by C<$0> (C<$PROGRAM_NAME> for users of F<English.pm>). 527 528If you are calling B<pod2usage()> from a module and want to display 529that module's POD, you can use this: 530 531 use Pod::Find qw(pod_where); 532 pod2usage( -input => pod_where({-inc => 1}, __PACKAGE__) ); 533 534=item C<-pathlist> I<string> 535 536A list of directory paths. If the input file does not exist, then it 537will be searched for in the given directory list (in the order the 538directories appear in the list). It defaults to the list of directories 539implied by C<$ENV{PATH}>. The list may be specified either by a reference 540to an array, or by a string of directory paths which use the same path 541separator as C<$ENV{PATH}> on your system (e.g., C<:> for Unix, C<;> for 542MSWin32 and DOS). 543 544=item C<-noperldoc> 545 546By default, Pod::Usage will call L<perldoc> when -verbose >= 2 is specified. 547This does not work well e.g. if the script was packed with L<PAR>. This option 548suppresses the external call to L<perldoc> and uses the simple text formatter 549(L<Pod::Text>) to output the POD. 550 551=item C<-perlcmd> 552 553By default, Pod::Usage will call L<perldoc> when -verbose >= 2 is 554specified. In case of special or unusual Perl installations, 555this option may be used to supply the path to a L<perl> executable 556which should run L<perldoc>. 557 558=item C<-perldoc> I<path-to-perldoc> 559 560By default, Pod::Usage will call L<perldoc> when -verbose >= 2 is 561specified. In case L<perldoc> is not installed where the L<perl> interpreter 562thinks it is (see L<Config>), the -perldoc option may be used to supply 563the correct path to L<perldoc>. 564 565=item C<-perldocopt> I<string> 566 567By default, Pod::Usage will call L<perldoc> when -verbose >= 2 is specified. 568This option may be used to supply options to L<perldoc>. The 569string may contain several, space-separated options. 570 571=back 572 573=head2 Formatting base class 574 575The default text formatter is L<Pod::Text>. The base class for Pod::Usage can 576be defined by pre-setting C<$Pod::Usage::Formatter> I<before> 577loading Pod::Usage, e.g.: 578 579 BEGIN { $Pod::Usage::Formatter = 'Pod::Text::Termcap'; } 580 use Pod::Usage qw(pod2usage); 581 582Pod::Usage uses L<Pod::Simple>'s _handle_element_end() method to implement 583the section selection, and in case of verbosity < 2 it down-cases the 584all-caps headings to first capital letter and rest lowercase, and adds 585a colon/newline at the end of the headings, for better readability. Same for 586verbosity = 99. 587 588=head2 Pass-through options 589 590The following options are passed through to the underlying text formatter. 591See the manual pages of these modules for more information. 592 593 alt code indent loose margin quotes sentence stderr utf8 width 594 595=head1 DESCRIPTION 596 597B<pod2usage> will print a usage message for the invoking script (using 598its embedded pod documentation) and then exit the script with the 599desired exit status. The usage message printed may have any one of three 600levels of "verboseness": If the verbose level is 0, then only a synopsis 601is printed. If the verbose level is 1, then the synopsis is printed 602along with a description (if present) of the command line options and 603arguments. If the verbose level is 2, then the entire manual page is 604printed. 605 606Unless they are explicitly specified, the default values for the exit 607status, verbose level, and output stream to use are determined as 608follows: 609 610=over 4 611 612=item * 613 614If neither the exit status nor the verbose level is specified, then the 615default is to use an exit status of 2 with a verbose level of 0. 616 617=item * 618 619If an exit status I<is> specified but the verbose level is I<not>, then the 620verbose level will default to 1 if the exit status is less than 2 and 621will default to 0 otherwise. 622 623=item * 624 625If an exit status is I<not> specified but verbose level I<is> given, then 626the exit status will default to 2 if the verbose level is 0 and will 627default to 1 otherwise. 628 629=item * 630 631If the exit status used is less than 2, then output is printed on 632C<STDOUT>. Otherwise output is printed on C<STDERR>. 633 634=back 635 636Although the above may seem a bit confusing at first, it generally does 637"the right thing" in most situations. This determination of the default 638values to use is based upon the following typical Unix conventions: 639 640=over 4 641 642=item * 643 644An exit status of 0 implies "success". For example, B<diff(1)> exits 645with a status of 0 if the two files have the same contents. 646 647=item * 648 649An exit status of 1 implies possibly abnormal, but non-defective, program 650termination. For example, B<grep(1)> exits with a status of 1 if 651it did I<not> find a matching line for the given regular expression. 652 653=item * 654 655An exit status of 2 or more implies a fatal error. For example, B<ls(1)> 656exits with a status of 2 if you specify an illegal (unknown) option on 657the command line. 658 659=item * 660 661Usage messages issued as a result of bad command-line syntax should go 662to C<STDERR>. However, usage messages issued due to an explicit request 663to print usage (like specifying B<-help> on the command line) should go 664to C<STDOUT>, just in case the user wants to pipe the output to a pager 665(such as B<more(1)>). 666 667=item * 668 669If program usage has been explicitly requested by the user, it is often 670desirable to exit with a status of 1 (as opposed to 0) after issuing 671the user-requested usage message. It is also desirable to give a 672more verbose description of program usage in this case. 673 674=back 675 676B<pod2usage> does not force the above conventions upon you, but it will 677use them by default if you don't expressly tell it to do otherwise. The 678ability of B<pod2usage()> to accept a single number or a string makes it 679convenient to use as an innocent looking error message handling function: 680 681 use strict; 682 use Pod::Usage; 683 use Getopt::Long; 684 685 ## Parse options 686 my %opt; 687 GetOptions(\%opt, "help|?", "man", "flag1") || pod2usage(2); 688 pod2usage(1) if ($opt{help}); 689 pod2usage(-exitval => 0, -verbose => 2) if ($opt{man}); 690 691 ## Check for too many filenames 692 pod2usage("$0: Too many files given.\n") if (@ARGV > 1); 693 694Some user's however may feel that the above "economy of expression" is 695not particularly readable nor consistent and may instead choose to do 696something more like the following: 697 698 use strict; 699 use Pod::Usage qw(pod2usage); 700 use Getopt::Long qw(GetOptions); 701 702 ## Parse options 703 my %opt; 704 GetOptions(\%opt, "help|?", "man", "flag1") || 705 pod2usage(-verbose => 0); 706 707 pod2usage(-verbose => 1) if ($opt{help}); 708 pod2usage(-verbose => 2) if ($opt{man}); 709 710 ## Check for too many filenames 711 pod2usage(-verbose => 2, -message => "$0: Too many files given.\n") 712 if (@ARGV > 1); 713 714 715As with all things in Perl, I<there's more than one way to do it>, and 716B<pod2usage()> adheres to this philosophy. If you are interested in 717seeing a number of different ways to invoke B<pod2usage> (although by no 718means exhaustive), please refer to L<"EXAMPLES">. 719 720=head2 Scripts 721 722The Pod::Usage distribution comes with a script pod2usage which offers 723a command line interface to the functionality of Pod::Usage. See 724L<pod2usage>. 725 726 727=head1 EXAMPLES 728 729Each of the following invocations of C<pod2usage()> will print just the 730"SYNOPSIS" section to C<STDERR> and will exit with a status of 2: 731 732 pod2usage(); 733 734 pod2usage(2); 735 736 pod2usage(-verbose => 0); 737 738 pod2usage(-exitval => 2); 739 740 pod2usage({-exitval => 2, -output => \*STDERR}); 741 742 pod2usage({-verbose => 0, -output => \*STDERR}); 743 744 pod2usage(-exitval => 2, -verbose => 0); 745 746 pod2usage(-exitval => 2, -verbose => 0, -output => \*STDERR); 747 748Each of the following invocations of C<pod2usage()> will print a message 749of "Syntax error." (followed by a newline) to C<STDERR>, immediately 750followed by just the "SYNOPSIS" section (also printed to C<STDERR>) and 751will exit with a status of 2: 752 753 pod2usage("Syntax error."); 754 755 pod2usage(-message => "Syntax error.", -verbose => 0); 756 757 pod2usage(-msg => "Syntax error.", -exitval => 2); 758 759 pod2usage({-msg => "Syntax error.", -exitval => 2, -output => \*STDERR}); 760 761 pod2usage({-msg => "Syntax error.", -verbose => 0, -output => \*STDERR}); 762 763 pod2usage(-msg => "Syntax error.", -exitval => 2, -verbose => 0); 764 765 pod2usage(-message => "Syntax error.", 766 -exitval => 2, 767 -verbose => 0, 768 -output => \*STDERR); 769 770Each of the following invocations of C<pod2usage()> will print the 771"SYNOPSIS" section and any "OPTIONS" and/or "ARGUMENTS" sections to 772C<STDOUT> and will exit with a status of 1: 773 774 pod2usage(1); 775 776 pod2usage(-verbose => 1); 777 778 pod2usage(-exitval => 1); 779 780 pod2usage({-exitval => 1, -output => \*STDOUT}); 781 782 pod2usage({-verbose => 1, -output => \*STDOUT}); 783 784 pod2usage(-exitval => 1, -verbose => 1); 785 786 pod2usage(-exitval => 1, -verbose => 1, -output => \*STDOUT}); 787 788Each of the following invocations of C<pod2usage()> will print the 789entire manual page to C<STDOUT> and will exit with a status of 1: 790 791 pod2usage(-verbose => 2); 792 793 pod2usage({-verbose => 2, -output => \*STDOUT}); 794 795 pod2usage(-exitval => 1, -verbose => 2); 796 797 pod2usage({-exitval => 1, -verbose => 2, -output => \*STDOUT}); 798 799=head2 Recommended Use 800 801Most scripts should print some type of usage message to C<STDERR> when a 802command line syntax error is detected. They should also provide an 803option (usually C<-H> or C<-help>) to print a (possibly more verbose) 804usage message to C<STDOUT>. Some scripts may even wish to go so far as to 805provide a means of printing their complete documentation to C<STDOUT> 806(perhaps by allowing a C<-man> option). The following complete example 807uses B<Pod::Usage> in combination with B<Getopt::Long> to do all of these 808things: 809 810 use strict; 811 use Getopt::Long qw(GetOptions); 812 use Pod::Usage qw(pod2usage); 813 814 my $man = 0; 815 my $help = 0; 816 ## Parse options and print usage if there is a syntax error, 817 ## or if usage was explicitly requested. 818 GetOptions('help|?' => \$help, man => \$man) or pod2usage(2); 819 pod2usage(1) if $help; 820 pod2usage(-verbose => 2) if $man; 821 822 ## If no arguments were given, then allow STDIN to be used only 823 ## if it's not connected to a terminal (otherwise print usage) 824 pod2usage("$0: No files given.") if ((@ARGV == 0) && (-t STDIN)); 825 826 __END__ 827 828 =head1 NAME 829 830 sample - Using GetOpt::Long and Pod::Usage 831 832 =head1 SYNOPSIS 833 834 sample [options] [file ...] 835 836 Options: 837 -help brief help message 838 -man full documentation 839 840 =head1 OPTIONS 841 842 =over 4 843 844 =item B<-help> 845 846 Print a brief help message and exits. 847 848 =item B<-man> 849 850 Prints the manual page and exits. 851 852 =back 853 854 =head1 DESCRIPTION 855 856 B<This program> will read the given input file(s) and do something 857 useful with the contents thereof. 858 859 =cut 860 861=head1 CAVEATS 862 863By default, B<pod2usage()> will use C<$0> as the path to the pod input 864file. Unfortunately, not all systems on which Perl runs will set C<$0> 865properly (although if C<$0> is not found, B<pod2usage()> will search 866C<$ENV{PATH}> or else the list specified by the C<-pathlist> option). 867If this is the case for your system, you may need to explicitly specify 868the path to the pod docs for the invoking script using something 869similar to the following: 870 871 pod2usage(-exitval => 2, -input => "/path/to/your/pod/docs"); 872 873In the pathological case that a script is called via a relative path 874I<and> the script itself changes the current working directory 875(see L<perlfunc/chdir>) I<before> calling pod2usage, Pod::Usage will 876fail even on robust platforms. Don't do that. Or use L<FindBin> to locate 877the script: 878 879 use FindBin; 880 pod2usage(-input => $FindBin::Bin . "/" . $FindBin::Script); 881 882=head1 SUPPORT 883 884This module is managed in a GitHub repository, 885L<https://github.com/Dual-Life/Pod-Usage> Feel free to fork and contribute, or 886to clone and send patches! 887 888Please use L<https://github.com/Dual-Life/Pod-Usage/issues/new> to file a bug 889report. The previous ticketing system, 890L<https://rt.cpan.org/Dist/Display.html?Queue=Pod-Usage>, is deprecated for 891this package. 892 893More general questions or discussion about POD should be sent to the 894C<pod-people@perl.org> mail list. Send an empty email to 895C<pod-people-subscribe@perl.org> to subscribe. 896 897=head1 AUTHOR 898 899Marek Rouchal E<lt>marekr@cpan.orgE<gt> 900 901Nicolas R E<lt>nicolas@atoomic.orgE<gt> 902 903Brad Appleton E<lt>bradapp@enteract.comE<gt> 904 905Based on code for B<Pod::Text::pod2text()> written by 906Tom Christiansen E<lt>tchrist@mox.perl.comE<gt> 907 908=head1 LICENSE 909 910Pod::Usage (the distribution) is licensed under the same terms as Perl. 911 912=head1 ACKNOWLEDGMENTS 913 914Nicolas R (ATOOMIC) for setting up the Github repo and modernizing this 915package. 916 917rjbs for refactoring Pod::Usage to not use Pod::Parser any more. 918 919Steven McDougall E<lt>swmcd@world.std.comE<gt> for his help and patience with 920re-writing this manpage. 921 922=head1 SEE ALSO 923 924B<Pod::Usage> is now a standalone distribution, depending on 925L<Pod::Text> which in turn depends on L<Pod::Simple>. 926 927L<Pod::Perldoc>, L<Getopt::Long>, L<Pod::Find>, L<FindBin>, 928L<Pod::Text>, L<Pod::Text::Termcap>, L<Pod::Simple> 929 930=cut 931 932