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.\" Copyright 1993 Mitchum DSouza <m.dsouza@mrc-applied-psychology.cambridge.ac.uk>
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Modified Thu Dec 13 22:51:19 2001 by Martin Schulze <joey@infodrom.org>
.\" Modified 2001-12-14 aeb
.\"
.TH CATOPEN 3 2001-12-14 "GNU" "Linux Programmer's Manual"
.SH NAME
catopen, catclose \- open/close a message catalog
.SH SYNOPSIS
.B #include <nl_types.h>
.sp
.BI "nl_catd catopen(const char *" name ", int " flag );
.br
.BI "int catclose(nl_catd " catalog );
.SH DESCRIPTION
The function
.BR catopen ()
opens a message catalog and returns a catalog descriptor.
The descriptor remains valid until
.BR catclose ()
or
.BR execve (2).
If a file descriptor is used to implement catalog descriptors
then the
.B FD_CLOEXEC
flag will be set.
.LP
The argument
.I name
specifies the name of the message catalog to be opened.
If
.I name
specifies and absolute path (i.e., contains a '/'),
then
.I name
specifies a pathname for the message catalog.
Otherwise, the environment variable
.B NLSPATH
is used with
.I name
substituted for
.B %N
(see
.BR locale (7)).
It is unspecified whether
.B NLSPATH
will be used when the process has root privileges.
If
.B NLSPATH
does not exist in the environment,
or if a message catalog cannot be opened
in any of the paths specified by it,
then an implementation defined path is used.
This latter default path may depend on the
.B LC_MESSAGES
locale setting when the
.I flag
argument is
.B NL_CAT_LOCALE
and on the
.B LANG
environment variable when the
.I flag
argument is 0.
Changing the
.B LC_MESSAGES
part of the locale may invalidate
open catalog descriptors.
.LP
The
.I flag
argument to
.BR catopen ()
is used to indicate the source for the language to use.
If it is set to
.B NL_CAT_LOCALE
then it will use the current locale setting for
.BR LC_MESSAGES .
Otherwise it will use the
.B LANG
environment variable.
.LP
The function
.BR catclose ()
closes the message catalog identified by
.IR catalog .
It invalidates any subsequent references to the message catalog
defined by
.IR catalog .
.SH "RETURN VALUE"
The function
.BR catopen ()
returns a message catalog descriptor of type
.I nl_catd
on success.
On failure, it returns \fI(nl_catd)\ \-1\fP
and sets
.I errno
to indicate the error.
The possible error values include all
possible values for the
.BR open (2)
call.
.LP
The function
.BR catclose ()
returns 0 on success, or \-1 on failure.
.SH ENVIRONMENT
.TP
.B LC_MESSAGES
May be the source of the
.B LC_MESSAGES
locale setting, and thus
determine the language to use if
.I flag
is set to
.BR NL_CAT_LOCALE .
.TP
.B LANG
The language to use if
.I flag
is 0.
.SH "CONFORMING TO"
POSIX.1-2001.
.\" In XPG 1987, Vol. 3 it says:
.\" .I "The flag argument of catopen is reserved for future use"
.\" .IR "and should be set to 0" .
It is unclear what the source was for the constants
.B MCLoadBySet
and
.B MCLoadAll
(see below).
.SH NOTES
The above is the POSIX.1-2001 description.
The glibc value for
.B NL_CAT_LOCALE
is 1.
(Compare
.B MCLoadAll
below.)
The default path varies, but usually looks at a number of places below
.IR /usr/share/locale .
.SS Linux Notes
These functions are available for Linux since libc 4.4.4c.
In the case of linux libc4 and libc5, the catalog descriptor
.I nl_catd
is a
.BR mmap (2)'ed
area of memory and not a file descriptor.
The
.I flag
argument to
.BR catopen ()
should be either
.B MCLoadBySet
(=0) or
.B MCLoadAll
(=1).
The former value indicates that a set from the catalog is to be
loaded when needed, whereas the latter causes the initial call to
.BR catopen ()
to load the entire catalog into memory.
The default search path varies, but usually looks at a number of places below
.I /etc/locale
and
.IR /usr/lib/locale .
.SH "SEE ALSO"
.BR catgets (3),
.BR setlocale (3)
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