endgrent(3)

1getgrent(3)                Library Functions Manual                getgrent(3)
2
3
4

NAME

6       getgrent, setgrent, endgrent - get group file entry
7

LIBRARY

9       Standard C library (libc, -lc)
10

SYNOPSIS

12       #include <sys/types.h>
13       #include <grp.h>
14
15       struct group *getgrent(void);
16
17       void setgrent(void);
18       void endgrent(void);
19
20   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
21
22       setgrent():
23           _XOPEN_SOURCE >= 500
24               || /* glibc >= 2.19: */ _DEFAULT_SOURCE
25               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
26
27       getgrent(), endgrent():
28           Since glibc 2.22:
29               _XOPEN_SOURCE >= 500 || _DEFAULT_SOURCE
30           glibc 2.21 and earlier
31               _XOPEN_SOURCE >= 500
32                   || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
33                   || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
34

DESCRIPTION

36       The getgrent() function returns a pointer to a structure containing the
37       broken-out fields of a record in the group database  (e.g.,  the  local
38       group  file  /etc/group,  NIS, and LDAP).  The first time getgrent() is
39       called, it returns the first entry; thereafter, it  returns  successive
40       entries.
41
42       The setgrent() function rewinds to the beginning of the group database,
43       to allow repeated scans.
44
45       The endgrent() function is used to close the group database  after  all
46       processing has been performed.
47
48       The group structure is defined in <grp.h> as follows:
49
50           struct group {
51               char   *gr_name;        /* group name */
52               char   *gr_passwd;      /* group password */
53               gid_t   gr_gid;         /* group ID */
54               char  **gr_mem;         /* NULL-terminated array of pointers
55                                          to names of group members */
56           };
57
58       For more information about the fields of this structure, see group(5).
59

RETURN VALUE

61       The getgrent() function returns a pointer to a group structure, or NULL
62       if there are no more entries or an error occurs.
63
64       Upon error, errno may be set.  If one wants to check  errno  after  the
65       call, it should be set to zero before the call.
66
67       The  return value may point to a static area, and may be overwritten by
68       subsequent calls to getgrent(), getgrgid(3), or getgrnam(3).   (Do  not
69       pass the returned pointer to free(3).)
70

ERRORS

72       EAGAIN The  service  was temporarily unavailable; try again later.  For
73              NSS backends in glibc this indicates a temporary  error  talking
74              to the backend.  The error may correct itself, retrying later is
75              suggested.
76
77       EINTR  A signal was caught; see signal(7).
78
79       EIO    I/O error.
80
81       EMFILE The per-process limit on the number of open file descriptors has
82              been reached.
83
84       ENFILE The system-wide limit on the total number of open files has been
85              reached.
86
87       ENOENT A necessary input file cannot be found.   For  NSS  backends  in
88              glibc this indicates the backend is not correctly configured.
89
90       ENOMEM Insufficient memory to allocate group structure.
91
92       ERANGE Insufficient buffer space supplied.
93

FILES

95       /etc/group
96              local group database file
97

ATTRIBUTES

99       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
100       tributes(7).
101
102       ┌────────────┬───────────────┬─────────────────────────────────────────┐
103       │Interface   │ Attribute     │ Value                                   │
104       ├────────────┼───────────────┼─────────────────────────────────────────┤
105       │getgrent()  │ Thread safety │ MT-Unsafe race:grent race:grentbuf      │
106       │            │               │ locale                                  │
107       ├────────────┼───────────────┼─────────────────────────────────────────┤
108       │setgrent(), │ Thread safety │ MT-Unsafe race:grent locale             │
109       │endgrent()  │               │                                         │
110       └────────────┴───────────────┴─────────────────────────────────────────┘
111
112       In the above table, grent in race:grent signifies that if  any  of  the
113       functions setgrent(), getgrent(), or endgrent() are used in parallel in
114       different threads of a program, then data races could occur.
115

STANDARDS

117       POSIX.1-2008.
118

HISTORY

120       POSIX.1-2001, SVr4, 4.3BSD.
121