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


       #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, size_t 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 ||


       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

       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 want to check only 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.




       For an explanation of the terms used in this section, see attributes(7).

       │InterfaceAttributeValue                   │
       │setnetgrent(),   │ Thread safety │ MT-Unsafe race:netgrent │
       │getnetgrent_r(), │               │ locale                  │
       │innetgr()        │               │                         │
       │endnetgrent()    │ Thread safety │ MT-Unsafe race:netgrent │
       │getnetgrent()    │ Thread safety │ MT-Unsafe race:netgrent │
       │                 │               │ race:netgrentbuf locale │
       In the above table, netgrent in race:netgrent signifies  that  if  any  of  the  functions
       setnetgrent(3),  getnetgrent_r(3),  innetgr(3), getnetgrent(3), or endnetgrent(3) are used
       in parallel in different threads of a program, then data races could occur.


       These functions are not in POSIX.1, 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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