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man:getnetgrent_r

SETNETGRENT(3) Linux Programmer's Manual 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  net-
     group-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, user-
     name, 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).
     allbox; lbw16 lb lbw23 l l  l.   Interface Attribute Value  T{  setnet-
     grent(),
     getnetgrent_r(),
     innetgr() T}   Thread safety  T{ MT-Unsafe race:netgrent
     locale  T} T{ endnetgrent() T}   Thread safety  MT-Unsafe race:netgrent
     T{ getnetgrent() T}   Thread safety  T{ MT-Unsafe race:netgrent
     race:netgrentbuf locale T}
     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  pro-
     gram, 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.   get-
     netgrent_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 4.16 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/.

GNU 2017-09-15 SETNETGRENT(3)

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