GETGRENT(3) | Library Functions Manual | GETGRENT(3) |
getgrent
, getgrent_r
,
getgrgid
, getgrgid_r
,
getgrnam
, getgrnam_r
,
setgroupent
, setgrent
,
endgrent
—
#include <grp.h>
struct group *
getgrent
(void);
int
getgrent_r
(struct group *grp,
char *buffer, size_t buflen,
struct group **result);
struct group *
getgrgid
(gid_t
gid);
int
getgrgid_r
(gid_t gid,
struct group *grp, char *buffer,
size_t buflen, struct group
**result);
struct group *
getgrnam
(const
char *name);
int
getgrnam_r
(const char *name,
struct group *grp, char *buffer,
size_t buflen, struct group
**result);
int
setgroupent
(int
stayopen);
void
setgrent
(void);
void
endgrent
(void);
<grp.h>
:
struct group { char *gr_name; /* group name */ char *gr_passwd; /* group password */ gid_t gr_gid; /* group id */ char **gr_mem; /* group members */ };
The functions getgrnam
() and
getgrgid
() search the group database for the given
group name pointed to by name or the group id pointed
to by gid, respectively, returning the first one
encountered. Identical group names or group ids may result in undefined
behavior.
The getgrent
() function sequentially reads
the group database and is intended for programs that wish to step through
the complete list of groups.
All three functions will open the group file for reading, if necessary.
The functions getgrnam_r
(),
getgrgid_r
(), and
getgrent_r
() act like their non re-entrant
counterparts respectively, updating the contents of
grp and storing a pointer to that in
result, and returning 0
.
Storage used by grp is allocated from
buffer, which is buflen bytes in
size. If the requested entry cannot be found, result
will point to NULL
and 0
will be returned. If an error occurs, a non-zero error number will be
returned and result will point to
NULL
. Calling getgrent_r
()
from multiple threads will result in each thread reading a disjoint portion
of the group database.
The setgroupent
() function opens the file,
or rewinds it if it is already open. If stayopen is
non-zero, file descriptors are left open, significantly speeding functions
subsequent calls. This functionality is unnecessary for
getgrent
() as it doesn't close its file descriptors
by default. It should also be noted that it is dangerous for long-running
programs to use this functionality as the group file may be updated.
The setgrent
() function is equivalent to
setgroupent
() with an argument of zero.
The endgrent
() function closes any open
files.
getgrgid
(),
getgrnam
(), and getgrent
()
return a valid pointer to a group structure on success and a
NULL
pointer if the entry was not found or an error
occurred. If an error occurred, the global variable
errno
is set to indicate the nature of the failure.
The functions getgrgid_r
(),
getgrnam_r
(), and
getgrent_r
() return 0
on
success or entry not found, and non-zero on failure, setting the global
variable errno
to indicate the nature of the
failure.
The setgroupent
() function returns the
value 1 if successful, otherwise the value 0 is returned, setting the global
variable errno
to indicate the nature of the
failure.
The endgrent
() and
setgrent
() functions have no return value.
setgrfile
(), which allowed the
specification of alternative group databases, has been deprecated and is no
longer available.
getgrent
, getgrent_r
,
getgrnam
, getgrnam_r
,
getgrgid
, getgrgid_r
, and
setgroupent
:
EINTR
]EIO
]EMFILE
]ENFILE
]The following error code may be set in errno
for getgrent_r
, getgrnam_r
,
and getgrgid_r
:
ERANGE
]buffer
and
buflen
Other errno
values may be set depending on
the specific database backends.
getgrgid
() and getgrnam
()
functions conform to IEEE Std 1003.1-1990
(“POSIX.1”). The getgrgid_r
() and
getgrnam_r
() functions conform to
IEEE Std 1003.1c-1995 (“POSIX.1c”). The
endgrent
(), getgrent
(), and
setgrent
() functions conform to
X/Open Portability Guide Issue 4, Version 2
(“XPG4.2”) and IEEE Std 1003.1-2004
(“POSIX.1”) (XSI extension).
endgrent
(),
getgrent
(), getgrgid
(),
getgrnam
(), and setgrent
()
appeared in Version 7 AT&T UNIX. The
functions setgrfile
() and
setgroupent
() appeared in
4.3BSD-Reno. The functions
getgrgid_r
() and getgrnam_r
()
appeared in NetBSD 3.0.
getgrent
(),
getgrgid
(), getgrnam
(),
setgroupent
() and setgrent
()
leave their results in an internal static object and return a pointer to that
object. Subsequent calls to the same function will modify the same object.
The functions getgrent
(),
endgrent
(), setgroupent
(),
and setgrent
() are fairly useless in a networked
environment and should be avoided, if possible.
getgrent
() makes no attempt to suppress duplicate
information if multiple sources are specified in
nsswitch.conf(5)
February 7, 2018 | NetBSD 9.0 |