NAME

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

SYNOPSIS

       #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:
               _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 │
       │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.

CONFORMING TO

       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.

NOTES

       In the BSD implementation, setnetgrent() returns void.

SEE ALSO

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

COLOPHON

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