setgrent(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           _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
22           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED ||
23           /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
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25       getgrent(), endgrent():
26           _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
27           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
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DESCRIPTION

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

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

65       EINTR  A signal was caught.
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67       EIO    I/O error.
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69       EMFILE The calling process already has too many open files.
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71       ENFILE Too many open files in the system.
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73       ENOMEM Insufficient memory to allocate group structure.
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75       ERANGE Insufficient buffer space supplied.
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FILES

78       /etc/group
79              local group database file
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ATTRIBUTES

82   Multithreading (see pthreads(7))
83       The getgrent() function is not thread-safe.
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85       The setgrent() and endgrent() functions are thread-safe.
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CONFORMING TO

88       SVr4, 4.3BSD, POSIX.1-2001.
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COLOPHON

95       This page is part of release 3.53 of the Linux  man-pages  project.   A
96       description  of  the project, and information about reporting bugs, can
97       be found at http://www.kernel.org/doc/man-pages/.
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101                                  2013-06-21                       GETGRENT(3)