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       catopen, catclose - open/close a message catalog


       #include <nl_types.h>

       nl_catd catopen(const char *name, int flag);

       int catclose(nl_catd catalog);


       The  function  catopen()  opens a message catalog and returns a catalog
       descriptor.   The  descriptor  remains  valid   until   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 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 LC_MESSAGES.  Otherwise it will use the LANG
       environment variable.

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


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


              May  be  the  source of the LC_MESSAGES locale setting, and thus
              determine the language to use if flag is set to NL_CAT_LOCALE.

       LANG   The language to use if flag is 0.


       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

   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  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 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


       catgets(3), setlocale(3)


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