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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | FILES | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
SETNETGRENT(3) Linux Programmer's Manual SETNETGRENT(3)
setnetgrent, endnetgrent, getnetgrent, getnetgrent_r, innetgr - han‐
dle network group entries
#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
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.
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.
In the BSD implementation, setnetgrent() returns void.
sethostent(3), setprotoent(3), setservent(3)
This page is part of release 4.12 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 2016-10-08 SETNETGRENT(3)
Pages that refer to this page: getent(1)