getnetgrent_r(3) — Linux manual page


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

NAME         top

       setnetgrent,  endnetgrent, getnetgrent, getnetgrent_r, innetgr - han‐
       dle network group entries

SYNOPSIS         top

       #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(),
           Since glibc 2.19:
           Glibc 2.19 and earlier:
               _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION         top

       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         top

       These functions return 1 on success and 0 for failure.

FILES         top


ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │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         top

       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         top

       In the BSD implementation, setnetgrent() returns void.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.08 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)