получить запись файла группы (get group file entry)
Имя (Name)
getgrent, setgrent, endgrent - get group file entry
Синопсис (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():
_XOPEN_SOURCE >= 500
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc <= 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 <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
Описание (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).
Возвращаемое значение (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).)
Ошибки (Error)
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.
Файлы (Files)
/etc/group
local group database file
Атрибуты (Attributes)
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(), │ Thread safety │ MT-Unsafe race:grent locale │
│endgrent() │ │ │
└────────────┴───────────────┴───────────────────────────────────┘
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.
Стандарты (Conforming to)
POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
Смотри также (See also)
fgetgrent(3), getgrent_r(3), getgrgid(3), getgrnam(3),
getgrouplist(3), putgrent(3), group(5)
