perllocale.1

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for the category.  You can use this value as the second argument in a
subsequent call to \fIsetlocale()\fR.
.PP
If no second argument is provided and the category is \s-1LC_ALL\s0, the
result is implementation-dependent.  It may be a string of
concatenated locales names (separator also implementation-dependent)
or a single locale name.  Please consult your \fIsetlocale\fR\|(3) man page for
details.
.PP
If a second argument is given and it corresponds to a valid locale,
the locale for the category is set to that value, and the function
returns the now-current locale value.  You can then use this in yet
another call to \fIsetlocale()\fR.  (In some implementations, the return
value may sometimes differ from the value you gave as the second
argument\*(--think of it as an alias for the value you gave.)
.PP
As the example shows, if the second argument is an empty string, the
category's locale is returned to the default specified by the
corresponding environment variables.  Generally, this results in a
return to the default that was in force when Perl started up: changes
to the environment made by the application after startup may or may not
be noticed, depending on your system's C library.
.PP
If the second argument does not correspond to a valid locale, the locale
for the category is not changed, and the function returns \fIundef\fR.
.PP
For further information about the categories, consult \fIsetlocale\fR\|(3).
.Sh "Finding locales"
.IX Subsection "Finding locales"
For locales available in your system, consult also \fIsetlocale\fR\|(3) to
see whether it leads to the list of available locales (search for the
\&\fI\s-1SEE\s0 \s-1ALSO\s0\fR section).  If that fails, try the following command lines:
.PP
.Vb 1
\&        locale \-a
\&
\&        nlsinfo
\&
\&        ls /usr/lib/nls/loc
\&
\&        ls /usr/lib/locale
\&
\&        ls /usr/lib/nls
\&
\&        ls /usr/share/locale
.Ve
.PP
and see whether they list something resembling these
.PP
.Vb 7
\&        en_US.ISO8859\-1     de_DE.ISO8859\-1     ru_RU.ISO8859\-5
\&        en_US.iso88591      de_DE.iso88591      ru_RU.iso88595
\&        en_US               de_DE               ru_RU
\&        en                  de                  ru
\&        english             german              russian
\&        english.iso88591    german.iso88591     russian.iso88595
\&        english.roman8                          russian.koi8r
.Ve
.PP
Sadly, even though the calling interface for \fIsetlocale()\fR has been
standardized, names of locales and the directories where the
configuration resides have not been.  The basic form of the name is
\&\fIlanguage_territory\fR\fB.\fR\fIcodeset\fR, but the latter parts after
\&\fIlanguage\fR are not always present.  The \fIlanguage\fR and \fIcountry\fR
are usually from the standards \fB\s-1ISO\s0 3166\fR and \fB\s-1ISO\s0 639\fR, the
two-letter abbreviations for the countries and the languages of the
world, respectively.  The \fIcodeset\fR part often mentions some \fB\s-1ISO\s0
8859\fR character set, the Latin codesets.  For example, \f(CW\*(C`ISO 8859\-1\*(C'\fR
is the so-called \*(L"Western European codeset\*(R" that can be used to encode
most Western European languages adequately.  Again, there are several
ways to write even the name of that one standard.  Lamentably.
.PP
Two special locales are worth particular mention: \*(L"C\*(R" and \*(L"\s-1POSIX\s0\*(R".
Currently these are effectively the same locale: the difference is
mainly that the first one is defined by the C standard, the second by
the \s-1POSIX\s0 standard.  They define the \fBdefault locale\fR in which
every program starts in the absence of locale information in its
environment.  (The \fIdefault\fR default locale, if you will.)  Its language
is (American) English and its character codeset \s-1ASCII\s0.
.PP
\&\fB\s-1NOTE\s0\fR: Not all systems have the \*(L"\s-1POSIX\s0\*(R" locale (not all systems are
POSIX-conformant), so use \*(L"C\*(R" when you need explicitly to specify this
default locale.
.Sh "\s-1LOCALE\s0 \s-1PROBLEMS\s0"
.IX Subsection "LOCALE PROBLEMS"
You may encounter the following warning message at Perl startup:
.PP
.Vb 6
\&        perl: warning: Setting locale failed.
\&        perl: warning: Please check that your locale settings:
\&                LC_ALL = "En_US",
\&                LANG = (unset)
\&            are supported and installed on your system.
\&        perl: warning: Falling back to the standard locale ("C").
.Ve
.PP
This means that your locale settings had \s-1LC_ALL\s0 set to \*(L"En_US\*(R" and
\&\s-1LANG\s0 exists but has no value.  Perl tried to believe you but could not.
Instead, Perl gave up and fell back to the \*(L"C\*(R" locale, the default locale
that is supposed to work no matter what.  This usually means your locale
settings were wrong, they mention locales your system has never heard
of, or the locale installation in your system has problems (for example,
some system files are broken or missing).  There are quick and temporary
fixes to these problems, as well as more thorough and lasting fixes.
.Sh "Temporarily fixing locale problems"
.IX Subsection "Temporarily fixing locale problems"
The two quickest fixes are either to render Perl silent about any
locale inconsistencies or to run Perl under the default locale \*(L"C\*(R".
.PP
Perl's moaning about locale problems can be silenced by setting the
environment variable \s-1PERL_BADLANG\s0 to a zero value, for example \*(L"0\*(R".
This method really just sweeps the problem under the carpet: you tell
Perl to shut up even when Perl sees that something is wrong.  Do not
be surprised if later something locale-dependent misbehaves.
.PP
Perl can be run under the \*(L"C\*(R" locale by setting the environment
variable \s-1LC_ALL\s0 to \*(L"C\*(R".  This method is perhaps a bit more civilized
than the \s-1PERL_BADLANG\s0 approach, but setting \s-1LC_ALL\s0 (or
other locale variables) may affect other programs as well, not just
Perl.  In particular, external programs run from within Perl will see
these changes.  If you make the new settings permanent (read on), all
programs you run see the changes.  See \*(L"\s-1ENVIRONMENT\s0\*(R" for
the full list of relevant environment variables and \*(L"\s-1USING\s0 \s-1LOCALES\s0\*(R"
for their effects in Perl.  Effects in other programs are 
easily deducible.  For example, the variable \s-1LC_COLLATE\s0 may well affect
your \fBsort\fR program (or whatever the program that arranges \*(L"records\*(R"
alphabetically in your system is called).
.PP
You can test out changing these variables temporarily, and if the
new settings seem to help, put those settings into your shell startup
files.  Consult your local documentation for the exact details.  For in
Bourne-like shells (\fBsh\fR, \fBksh\fR, \fBbash\fR, \fBzsh\fR):
.PP
.Vb 2
\&        LC_ALL=en_US.ISO8859\-1
\&        export LC_ALL
.Ve
.PP
This assumes that we saw the locale \*(L"en_US.ISO8859\-1\*(R" using the commands
discussed above.  We decided to try that instead of the above faulty
locale \*(L"En_US\*(R"\-\-and in Cshish shells (\fBcsh\fR, \fBtcsh\fR)
.PP
.Vb 1
\&        setenv LC_ALL en_US.ISO8859\-1
.Ve
.PP
or if you have the \*(L"env\*(R" application you can do in any shell
.PP
.Vb 1
\&        env LC_ALL=en_US.ISO8859\-1 perl ...
.Ve
.PP
If you do not know what shell you have, consult your local
helpdesk or the equivalent.
.Sh "Permanently fixing locale problems"
.IX Subsection "Permanently fixing locale problems"
The slower but superior fixes are when you may be able to yourself
fix the misconfiguration of your own environment variables.  The
mis(sing)configuration of the whole system's locales usually requires
the help of your friendly system administrator.
.PP
First, see earlier in this document about \*(L"Finding locales\*(R".  That tells
how to find which locales are really supported\*(--and more importantly,
installed\*(--on your system.  In our example error message, environment
variables affecting the locale are listed in the order of decreasing
importance (and unset variables do not matter).  Therefore, having
\&\s-1LC_ALL\s0 set to \*(L"En_US\*(R" must have been the bad choice, as shown by the
error message.  First try fixing locale settings listed first.
.PP
Second, if using the listed commands you see something \fBexactly\fR
(prefix matches do not count and case usually counts) like \*(L"En_US\*(R"
without the quotes, then you should be okay because you are using a
locale name that should be installed and available in your system.
In this case, see \*(L"Permanently fixing your system's locale configuration\*(R".
.Sh "Permanently fixing your system's locale configuration"
.IX Subsection "Permanently fixing your system's locale configuration"
This is when you see something like:
.PP
.Vb 4
\&        perl: warning: Please check that your locale settings:
\&                LC_ALL = "En_US",
\&                LANG = (unset)
\&            are supported and installed on your system.
.Ve
.PP
but then cannot see that \*(L"En_US\*(R" listed by the above-mentioned
commands.  You may see things like \*(L"en_US.ISO8859\-1\*(R", but that isn't
the same.  In this case, try running under a locale
that you can list and which somehow matches what you tried.  The
rules for matching locale names are a bit vague because
standardization is weak in this area.  See again the 
\&\*(L"Finding locales\*(R" about general rules.
.Sh "Fixing system locale configuration"
.IX Subsection "Fixing system locale configuration"
Contact a system administrator (preferably your own) and report the exact
error message you get, and ask them to read this same documentation you
are now reading.  They should be able to check whether there is something
wrong with the locale configuration of the system.  The \*(L"Finding locales\*(R"
section is unfortunately a bit vague about the exact commands and places
because these things are not that standardized.
.Sh "The localeconv function"
.IX Subsection "The localeconv function"
The \fIPOSIX::localeconv()\fR function allows you to get particulars of the
locale-dependent numeric formatting information specified by the current
\&\f(CW\*(C`LC_NUMERIC\*(C'\fR and \f(CW\*(C`LC_MONETARY\*(C'\fR locales.  (If you just want the name of
the current locale for a particular category, use \fIPOSIX::setlocale()\fR
with a single parameter\*(--see \*(L"The setlocale function\*(R".)
.PP
.Vb 1
\&        use POSIX qw(locale_h);
\&
\&        # Get a reference to a hash of locale\-dependent info
\&        $locale_values = localeconv();
\&
\&        # Output sorted list of the values
\&        for (sort keys %$locale_values) {
\&            printf "%\-20s = %s\en", $_, $locale_values\->{$_}
\&        }
.Ve
.PP
\&\fIlocaleconv()\fR takes no arguments, and returns \fBa reference to\fR a hash.
The keys of this hash are variable names for formatting, such as
\&\f(CW\*(C`decimal_point\*(C'\fR and \f(CW\*(C`thousands_sep\*(C'\fR.  The values are the
corresponding, er, values.  See \*(L"localeconv\*(R" in \s-1POSIX\s0 for a longer
example listing the categories an implementation might be expected to
provide; some provide more and others fewer.  You don't need an
explicit \f(CW\*(C`use locale\*(C'\fR, because \fIlocaleconv()\fR always observes the
current locale.
.PP
Here's a simple-minded example program that rewrites its command-line
parameters as integers correctly formatted in the current locale:
.PP
.Vb 3
\&        # See comments in previous example
\&        require 5.004;
\&        use POSIX qw(locale_h);
\&
\&        # Get some of locale\*(Aqs numeric formatting parameters
\&        my ($thousands_sep, $grouping) =
\&             @{localeconv()}{\*(Aqthousands_sep\*(Aq, \*(Aqgrouping\*(Aq};
\&
\&        # Apply defaults if values are missing
\&        $thousands_sep = \*(Aq,\*(Aq unless $thousands_sep;
\&
\&        # grouping and mon_grouping are packed lists
\&        # of small integers (characters) telling the
\&        # grouping (thousand_seps and mon_thousand_seps
\&        # being the group dividers) of numbers and
\&        # monetary quantities.  The integers\*(Aq meanings:
\&        # 255 means no more grouping, 0 means repeat
\&        # the previous grouping, 1\-254 means use that
\&        # as the current grouping.  Grouping goes from
\&        # right to left (low to high digits).  In the
\&        # below we cheat slightly by never using anything
\&        # else than the first grouping (whatever that is).
\&        if ($grouping) {
\&            @grouping = unpack("C*", $grouping);
\&        } else {
\&            @grouping = (3);
\&        }
\&
\&        # Format command line params for current locale
\&        for (@ARGV) {
\&            $_ = int;    # Chop non\-integer part
\&            1 while
\&            s/(\ed)(\ed{$grouping[0]}($|$thousands_sep))/$1$thousands_sep$2/;
\&            print "$_";
\&        }
\&        print "\en";
.Ve
.Sh "I18N::Langinfo"
.IX Subsection "I18N::Langinfo"
Another interface for querying locale-dependent information is the
\&\fII18N::Langinfo::langinfo()\fR function, available at least in UNIX-like
systems and \s-1VMS\s0.
.PP
The following example will import the \fIlanginfo()\fR function itself and
three constants to be used as arguments to \fIlanginfo()\fR: a constant for
the abbreviated first day of the week (the numbering starts from