GETGRENT(3) Linux Programmer's Manual GETGRENT(3)NAME
getgrent, setgrent, endgrent - get group file entry
SYNOPSIS
#include <sys/types.h>
#include <grp.h>
struct group *getgrent(void);
void setgrent(void);
void endgrent(void);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
setgrent():
_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED ||
/* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
getgrent(), endgrent():
_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
_XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
DESCRIPTION
The getgrent() function returns a pointer to a structure containing the
broken-out fields of a record in the group database (e.g., the local
group file /etc/group, NIS, and LDAP). The first time getgrent() is
called, it returns the first entry; thereafter, it returns successive
entries.
The setgrent() function rewinds to the beginning of the group database,
to allow repeated scans.
The endgrent() function is used to close the group database after all
processing has been performed.
The group structure is defined in <grp.h> as follows:
struct group {
char *gr_name; /* group name */
char *gr_passwd; /* group password */
gid_t gr_gid; /* group ID */
char **gr_mem; /* group members */
};
For more information about the fields of this structure, see group(5).
RETURN VALUE
The getgrent() function returns a pointer to a group structure, or NULL
if there are no more entries or an error occurs.
Upon error, errno may be set. If one wants to check errno after the
call, it should be set to zero before the call.
The return value may point to a static area, and may be overwritten by
subsequent calls to getgrent(), getgrgid(3), or getgrnam(3). (Do not
pass the returned pointer to free(3).)
ERRORS
EINTR A signal was caught.
EIO I/O error.
EMFILE The calling process already has too many open files.
ENFILE Too many open files in the system.
ENOMEM Insufficient memory to allocate group structure.
ERANGE Insufficient buffer space supplied.
FILES
/etc/group
local group database file
ATTRIBUTES
Multithreading (see pthreads(7))
The getgrent() function is not thread-safe.
The setgrent() and endgrent() functions are thread-safe.
CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001.
SEE ALSOfgetgrent(3), getgrent_r(3), getgrgid(3), getgrnam(3), getgrouplist(3),
putgrent(3), group(5)COLOPHON
This page is part of release 3.63 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2013-06-21 GETGRENT(3)
