1SETNETGRENT(3) Linux Programmer's Manual SETNETGRENT(3)
2
6 setnetgrent, endnetgrent, getnetgrent, getnetgrent_r, innetgr - handle
7 network group entries
8
10 #include <netdb.h>
11 int setnetgrent(const char *netgroup);
13 void endnetgrent(void);
15 int getnetgrent(char **host, char **user, char **domain);
17 int getnetgrent_r(char **host, char **user,
19 char **domain, char *buf, size_t buflen);
20 int innetgr(const char *netgroup, const char *host,
22 const char *user, const char *domain);
23 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
25 setnetgrent(), endnetgrent(), getnetgrent(), getnetgrent_r(),
27 innetgr():
28 Since glibc 2.19:
29 _DEFAULT_SOURCE
30 Glibc 2.19 and earlier:
31 _BSD_SOURCE || _SVID_SOURCE
32
34 The netgroup is a SunOS invention. A netgroup database is a list of
35 string triples (hostname, username, domainname) or other netgroup
36 names. Any of the elements in a triple can be empty, which means that
37 anything matches. The functions described here allow access to the
38 netgroup databases. The file /etc/nsswitch.conf defines what database
39 is searched.
40 The setnetgrent() call defines the netgroup that will be searched by
42 subsequent getnetgrent() calls. The getnetgrent() function retrieves
43 the next netgroup entry, and returns pointers in host, user, domain. A
44 null pointer means that the corresponding entry matches any string.
45 The pointers are valid only as long as there is no call to other net‐
46 group-related functions. To avoid this problem you can use the GNU
47 function getnetgrent_r() that stores the strings in the supplied buf‐
48 fer. To free all allocated buffers use endnetgrent().
49 In most cases you want to check only if the triplet (hostname, user‐
51 name, domainname) is a member of a netgroup. The function innetgr()
52 can be used for this without calling the above three functions. Again,
53 a null pointer is a wildcard and matches any string. The function is
54 thread-safe.
55
57 These functions return 1 on success and 0 for failure.
58
60 /etc/netgroup
61 /etc/nsswitch.conf
62
64 For an explanation of the terms used in this section, see
65 attributes(7).
66 ┌─────────────────┬───────────────┬─────────────────────────┐
68 │Interface │ Attribute │ Value │
69 ├─────────────────┼───────────────┼─────────────────────────┤
70 │setnetgrent(), │ Thread safety │ MT-Unsafe race:netgrent │
71 │getnetgrent_r(), │ │ locale │
72 │innetgr() │ │ │
73 ├─────────────────┼───────────────┼─────────────────────────┤
74 │endnetgrent() │ Thread safety │ MT-Unsafe race:netgrent │
75 ├─────────────────┼───────────────┼─────────────────────────┤
76 │getnetgrent() │ Thread safety │ MT-Unsafe race:netgrent │
77 │ │ │ race:netgrentbuf locale │
78 └─────────────────┴───────────────┴─────────────────────────┘
79 In the above table, netgrent in race:netgrent signifies that if any of
80 the functions setnetgrent(), getnetgrent_r(), innetgr(), getnetgrent(),
81 or endnetgrent() are used in parallel in different threads of a pro‐
82 gram, then data races could occur.
83
85 These functions are not in POSIX.1, but setnetgrent(), endnetgrent(),
86 getnetgrent(), and innetgr() are available on most UNIX systems. get‐
87 netgrent_r() is not widely available on other systems.
88
90 In the BSD implementation, setnetgrent() returns void.
91
93 sethostent(3), setprotoent(3), setservent(3)
94
96 This page is part of release 4.16 of the Linux man-pages project. A
97 description of the project, information about reporting bugs, and the
98 latest version of this page, can be found at
99 https://www.kernel.org/doc/man-pages/.
100GNU 2017-09-15 SETNETGRENT(3)