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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; /* NULL-terminated array of pointers
to names of 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
EAGAIN The service was temporarily unavailable; try again later. For NSS backends in
glibc this indicates a temporary error talking to the backend. The error may cor‐
rect itself, retrying later is suggested.
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.
ENOENT A necessary input file cannot be found. For NSS backends in glibc this indicates
the backend is not correctly configured.
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 ALSO
fgetgrent(3), getgrent_r(3), getgrgid(3), getgrnam(3), getgrouplist(3), putgrent(3),
group(5)
COLOPHON
This page is part of release 3.74 of the Linux man-pages project. A description of the
project, information about reporting bugs, and the latest version of this page, can be
found at http://www.kernel.org/doc/man-pages/.
2014-10-02 GETGRENT(3)
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