NAME

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

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #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:
               _DEFAULT_SOURCE
           glibc 2.19 and earlier:
               _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       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  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.

RETURN VALUE

       These functions return 1 on success and 0 for failure.

FILES

       /etc/netgroup
       /etc/nsswitch.conf

ATTRIBUTES

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

       ┌───────────────────────────┬───────────────┬────────────────────────────────────────────────────────────┐
       │Interface                  │ Attribute     │ Value                                                      │
       ├───────────────────────────┼───────────────┼────────────────────────────────────────────────────────────┤
       │setnetgrent(),             │ Thread safety │ MT-Unsafe race:netgrent locale                             │
       │getnetgrent_r(), 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.

VERSIONS

       In the BSD implementation, setnetgrent() returns void.

STANDARDS

       None.

HISTORY

       setnetgrent(),  endnetgrent(),  getnetgrent(),  and  innetgr()  are  available  on  most  UNIX   systems.
       getnetgrent_r() is not widely available on other systems.

SEE ALSO

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