| Standards / Extensions | C or C++ | Dependencies |
|---|---|---|
XPG4 |
both |
#define _XOPEN_SOURCE
#include <nl_types.h>
nl_catd catopen(const char *name, int oflag);The catopen() function opens a message catalog and returns a message catalog descriptor. The name argument specifies the name of the message catalog to be opened. If name contains a "/", then name specifies a complete name for the message catalog. Otherwise, the environment variable NLSPATH is used with name substituted for %N (see the XBD specification, topic Environment Variables). If NLSPATH does not exist in the environment, or if a message catalog cannot be found in any of the components specified by NLSPATH, then the default path of "/usr/lib/nls/msg/%L/%N" is used. The "%L" component of this default path is replaced by the setting of LC_MESSAGES if the value of oflag is NL_CAT_LOCALE, or the LANG environment variable if oflag is 0. A change in the setting of the LANG or LC_MESSAGES will have no effect on existing open catalogs.
A message catalog descriptor remains valid in a process until that process closes it, or a successful call to one of the exec functions. When a message catalog is opened the FD_CLOEXEC flag will be set. See fcntl() — Control open file descriptors. Portable applications must assume that message catalog descriptors are not valid after a call to one of the exec functions.
If a catalog is opened more than once in the same process, a use count is incremented. When the use count reaches zero, by using catclose() to close the catalog, then the file descriptor for that catalog is closed.
If successful, catopen() returns a message catalog descriptor for use on subsequent calls to catgets() and catclose().