setnetgrent(3)                                        Library Functions Manual                                       setnetgrent(3)

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

       Standard C library (libc, -lc)

       #include <netdb.h>

       int setnetgrent(const char *netgroup);
       void endnetgrent(void);

       int getnetgrent(char **restrict host,
                   char **restrict user, char **restrict domain);
       int getnetgrent_r(char **restrict host,
                   char **restrict user, char **restrict domain,
                   char buf[restrict .buflen], 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():
           Since glibc 2.19:
           glibc 2.19 and earlier:
               _BSD_SOURCE || _SVID_SOURCE

       The netgroup is a SunOS invention.  A netgroup database is a list of string triples (hostname, username, domainname) or oth‐
       er netgroup names.  Any of the elements in a triple can be empty, which means that  anything  matches.   The  functions  de‐
       scribed 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  cor‐
       responding  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  buf‐
       fer.  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 func‐
       tion 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).

       │Interface                       │ Attribute     │ Value                                                                    │
       │setnetgrent(), getnetgrent_r(), │ Thread safety │ MT-Unsafe race:netgrent 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(), getnetgrent_r(),  innet‐
       gr(), getnetgrent(), or endnetgrent() 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)

Linux man-pages 6.03                                         2023-02-05                                              setnetgrent(3)