getnetgrent

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
       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 5.04 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)