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15.5.21 Perl



Ubuntu packages

perl, libintl-perl

File extension

pl, PL, pm, perl, cgi

String syntax
  • "abc"
  • 'abc'
  • qq (abc)
  • q (abc)
  • qr /abc/
  • qx (/bin/date)
  • /pattern match/
  • ?pattern match?
  • s/substitution/operators/
  • $tied_hash{"message"}
  • $tied_hash_reference->{"message"}
  • etc., issue the command ‘man perlsyn’ for details
gettext shorthand

__ (double underscore)

gettext/ngettext functions

gettext, dgettext, dcgettext, ngettext, dngettext, dcngettext, pgettext, dpgettext, dcpgettext, npgettext, dnpgettext, dcnpgettext


textdomain function


bindtextdomain function


bind_textdomain_codeset function


Use setlocale (LC_ALL, "");


use POSIX;
use Locale::TextDomain; (included in the package libintl-perl which is available on the Comprehensive Perl Archive Network CPAN,

Use or emulate GNU gettext

platform dependent: gettext_pp emulates, gettext_xs uses GNU gettext


xgettext -k__ -k\$__ -k%__ -k__x -k__n:1,2 -k__nx:1,2 -k__xn:1,2 -kN__ -kN__n:1,2 -k__p:1c,2 -k__np:1c,2,3 -kN__p:1c,2 -kN__np:1c,2,3

Formatting with positions

Both kinds of format strings support formatting with positions.
printf "%2\$d %1\$d", ... (requires Perl 5.8.0 or newer)
__expand("[new] replaces [old]", old => $oldvalue, new => $newvalue)


The libintl-perl package is platform independent but is not part of the Perl core. The programmer is responsible for providing a dummy implementation of the required functions if the package is not installed on the target system.

po-mode marking


Included in libintl-perl, available on CPAN (

An example is available in the examples directory: hello-perl.

The xgettext parser backend for Perl differs significantly from the parser backends for other programming languages, just as Perl itself differs significantly from other programming languages. The Perl parser backend offers many more string marking facilities than the other backends but it also has some Perl specific limitations, the worst probably being its imperfectness.

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