getgrent, setgrent, endgrent - get group file entry
#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():
_XOPEN_SOURCE >= 500
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
getgrent(),
endgrent():
Since glibc 2.22:
_XOPEN_SOURCE >= 500 ||
_DEFAULT_SOURCE
Glibc 2.21 and earlier
_XOPEN_SOURCE >= 500
|| /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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).
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).)
- 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 correct itself, retrying later is suggested.
- EINTR
- A signal was caught; see signal(7).
- EIO
- I/O error.
- EMFILE
- The per-process limit on the number of open file descriptors has been
reached.
- ENFILE
- The system-wide limit on the total number of open files has been
reached.
- 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.
- /etc/group
- local group database file
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
getgrent () |
Thread safety |
MT-Unsafe race:grent race:grentbuf locale |
setgrent (), endgrent () |
Thread safety |
MT-Unsafe race:grent locale |
In the above table,
grent in
race:grent signifies that if any of
the functions
setgrent(),
getgrent(), or
endgrent() are
used in parallel in different threads of a program, then data races could
occur.
POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
fgetgrent(3),
getgrent_r(3),
getgrgid(3),
getgrnam(3),
getgrouplist(3),
putgrent(3),
group(5)