endgrent(3)

1GETGRENT(3)                Linux Programmer's Manual               GETGRENT(3)
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NAME

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

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

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

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

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

94       /etc/group
95              local group database file
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ATTRIBUTES

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

115       POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
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COLOPHON

122       This  page  is  part of release 5.10 of the Linux man-pages project.  A
123       description of the project, information about reporting bugs,  and  the
124       latest     version     of     this    page,    can    be    found    at
125       https://www.kernel.org/doc/man-pages/.
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129                                  2017-09-15                       GETGRENT(3)