catopen, catclose - open/close a message catalog

#include <nl_types.h> I nl_catd catopen(const char * name , int flag );
I int catclose(nl_catd catalog );

The function R catopen () opens a message catalog and returns a catalog descriptor. The descriptor remains valid until R catclose () or execve(2). If a file descriptor is used to implement catalog descriptors then the FD_CLOEXEC flag will be set.

The argument name specifies the name of the message catalog to be opened. If name specifies and absolute path (i.e., contains a '/'), then name specifies a pathname for the message catalog. Otherwise, the environment variable NLSPATH is used with name substituted for %N (see locale(7)). It is unspecified whether NLSPATH will be used when the process has root privileges. If 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 LC_MESSAGES locale setting when the flag argument is NL_CAT_LOCALE and on the LANG environment variable when the flag argument is 0. Changing the LC_MESSAGES part of the locale may invalidate open catalog descriptors.

The flag argument to R catopen () is used to indicate the source for the language to use. If it is set to NL_CAT_LOCALE then it will use the current locale setting for R LC_MESSAGES . Otherwise it will use the LANG environment variable.

The function R catclose () closes the message catalog identified by R catalog . It invalidates any subsequent references to the message catalog defined by R catalog .

The function R catopen () returns a message catalog descriptor of type nl_catd on success. On failure, it returns (nl_catd) -1 and sets errno to indicate the error. The possible error values include all possible values for the open(2) call.

The function R catclose () returns 0 on success, or -1 on failure.

LC_MESSAGES

LANG

POSIX.1-2001. It is unclear what the source was for the constants MCLoadBySet and MCLoadAll (see below).

The above is the POSIX.1-2001 description. The glibc value for NL_CAT_LOCALE is 1. (Compare MCLoadAll below.) The default path varies, but usually looks at a number of places below R /usr/share/locale .

Linux Notes

These functions are available for Linux since libc 4.4.4c. In the case of linux libc4 and libc5, the catalog descriptor nl_catd is a mmap(2)'ed area of memory and not a file descriptor. The flag argument to R catopen () should be either MCLoadBySet (=0) or 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 R catopen () to load the entire catalog into memory. The default search path varies, but usually looks at a number of places below /etc/locale and R /usr/lib/locale .

catgets(3), setlocale(3)