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       setnetgrent,  endnetgrent, getnetgrent, getnetgrent_r, innetgr - handle
       network group entries


       #include <netdb.h>

       int setnetgrent(const char *netgroup);

       void endnetgrent(void);

       int getnetgrent(char **host, char **user, char **domain);

       int getnetgrent_r(char **host, char **user,
                         char **domain, char *buf, int buflen);

       int innetgr(const char *netgroup, const char *host,
                   const char *user, const char *domain);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       setnetgrent(), endnetgrent(), getnetgrent(), getnetgrent_r(),
       innetgr(): _BSD_SOURCE || _SVID_SOURCE


       The  netgroup  is  a SunOS invention.  A netgroup database is a list of
       string triples  (hostname,  username,  domainname)  or  other  netgroup
       names.   Any of the elements in a triple can be empty, which means that
       anything matches.  The functions described here  allow  access  to  the
       netgroup  databases.  The file /etc/nsswitch.conf defines what database
       is searched.

       The setnetgrent() call defines the netgroup that will  be  searched  by
       subsequent  getnetgrent()  calls.  The getnetgrent() function retrieves
       the next netgroup entry, and returns pointers in host, user, domain.  A
       NULL  pointer  means  that  the corresponding entry matches any string.
       The pointers are valid only as long  as  there  is  no  call  to  other
       netgroup-related  functions.  To avoid this problem you can use the GNU
       function getnetgrent_r()  that  stores  the  strings  in  the  supplied
       buffer.  To free all allocated buffers use endnetgrent().

       In   most   cases   you   only   want   to   check   if   the   triplet
       (hostname,username,domainname) is a member of a netgroup.  The function
       innetgr()  can  be  used  for  this  without  calling  the  above three
       functions.  Again, a NULL pointer is a wildcard and matches any string.
       The function is thread-safe.


       These functions return 1 on success and 0 for failure.




       These   functions   are   not   in   POSIX.1-2001,  but  setnetgrent(),
       endnetgrent(), getnetgrent(), and innetgr() are available on most  Unix
       systems.  getnetgrent_r() is not widely available on other systems.


       In the BSD implementation, setnetgrent() returns void.


       sethostent(3), setprotoent(3), setservent(3)


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