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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | FILES | ATTRIBUTES | VERSIONS | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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setnetgrent(3) Library Functions Manual setnetgrent(3)
setnetgrent, endnetgrent, getnetgrent, getnetgrent_r, innetgr -
handle network group entries
Standard C library (libc, -lc)
#include <netdb.h>
int setnetgrent(const char *netgroup);
void endnetgrent(void);
int getnetgrent(char **restrict host,
char **restrict user, char **restrict domain);
int getnetgrent_r(size_t size;
char **restrict host,
char **restrict user, char **restrict domain,
char buf[restrict size], size_t size);
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
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.
These functions return 1 on success and 0 for failure.
/etc/netgroup
/etc/nsswitch.conf
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.
In the BSD implementation, setnetgrent() returns void.
None.
setnetgrent(), endnetgrent(), getnetgrent(), and innetgr() are
available on most UNIX systems. getnetgrent_r() is not widely
available on other systems.
sethostent(3), setprotoent(3), setservent(3)
This page is part of the man-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 is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-06-28 setnetgrent(3)
Pages that refer to this page: getent(1)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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