SETNETGRENT(3)              Linux Programmer's Manual             SETNETGRENT(3)

       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, 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 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-

       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(),   │ 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(), getnetgrent_r(), innetgr(), 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)

       This page is part of release 5.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

GNU                                2017-09-15                     SETNETGRENT(3)