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setnetgrent(3) — Linux manual page

setnetgrent(3)           Library Functions Manualsetnetgrent(3)

NAME        top

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

LIBRARY        top

       Standard C library (libc,-lc)

SYNOPSIS        top

#include <netdb.h>int setnetgrent(const char *netgroup);void endnetgrent(void);int getnetgrent(char **restricthost,char **restrictuser, char **restrictdomain);int getnetgrent_r(size_t size;char **restricthost,char **restrictuser, char **restrictdomain,charbuf[restrictsize], size_tsize);int innetgr(const char *netgroup, const char *host,const char *user, const char *domain);   Feature Test Macro Requirements for glibc (seefeature_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        top

       Thenetgroup 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.       Thesetnetgrent() call defines the netgroup that will be searched       by subsequentgetnetgrent() calls.  Thegetnetgrent() function       retrieves the next netgroup entry, and returns pointers inhost,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 functiongetnetgrent_r() that stores       the strings in the supplied buffer.  To free all allocated buffers       useendnetgrent().       In most cases you want to check only if the triplet (hostname,username,domainname) is a member of a netgroup.  The functioninnetgr() 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

/etc/netgroup/etc/nsswitch.conf

ATTRIBUTES        top

       For an explanation of the terms used in this section, seeattributes(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 inrace:netgrent signifies that if       any of the functionssetnetgrent(),getnetgrent_r(),innetgr(),getnetgrent(), orendnetgrent() are used in parallel in different       threads of a program, then data races could occur.

VERSIONS        top

       In the BSD implementation,setnetgrent() returns void.

STANDARDS        top

       None.

HISTORY        top

setnetgrent(),endnetgrent(),getnetgrent(), andinnetgr() are       available on most UNIX systems.getnetgrent_r() is not widely       available on other systems.

SEE ALSO        top

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

COLOPHON        top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-06-28setnetgrent(3)

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