setnetgrent(3)

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

   This  page  is  part of release 4.09 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
   https://www.kernel.org/doc/man-pages/.

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