NAME
getgrnam, getgrnam_r, getgrgid, getgrgid_r - get group file entry
SYNOPSIS
#include <sys/types.h>
#include <grp.h>
I struct group *getgrnam(const char * name );
I struct group *getgrgid(gid_t gid );
I int getgrnam_r(const char * name , struct group * gbuf ,
I char * buf , size_t buflen , struct group ** gbufp );
I int getgrgid_r(gid_t gid , struct group * gbuf ,
I char * buf , size_t buflen , struct group ** gbufp );
DESCRIPTION
The
R getgrnam ()
function returns a pointer to a structure containing
the broken-out fields of the record in the group database
(e.g., the local group file
R /etc/group ,
NIS, and LDAP)
that matches the group name
R name .
The
R getgrgid ()
function returns a pointer to a structure containing
the broken-out fields of the record in the group database
that matches the group ID
R gid .
The
R getgrnam_r ()
and
R getgrgid_r ()
functions obtain the same information, but store the retrieved
group
structure
in the space pointed to by
R gbuf .
This
group
structure contains pointers to strings, and these strings
are stored in the buffer
buf
of size
R buflen .
A pointer to the result (in case of success) or NULL (in case no entry
was found or an error occurred) is stored in
*gbufp.
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 */
};
The maximum needed size for
buf
can be found using
sysconf(3)
with the
_SC_GETGR_R_SIZE_MAX
parameter.
RETURN VALUE
The
R getgrnam ()
and
R getgrgid ()
functions return a pointer to a
group
structure, or NULL if the matching entry
is not found or an error occurs.
If an error occurs,
errno
is set appropriately.
If one wants to check
errno
after the call, it should be set to zero before the call.
The return value may point to static area, and may be overwritten
by subsequent calls to
getgrent(3),
R getgrgid (),
or
R getgrnam ().
The
R getgrnam_r ()
and
R getgrgid_r ()
functions return
zero on success.
In case of error, an error number is returned.
ERRORS
R 0 or ENOENT or ESRCH or EBADF or EPERM or ...
The given
name
or
gid
was not found.
EINTR
A signal was caught.
EMFILE
The maximum number
(OPEN_MAX)
of files was open already in the calling process.
ENFILE
The maximum number of files was open already in the system.
ENOMEM
Insufficient memory to allocate group structure.
ERANGE
Insufficient buffer space supplied.
FILES
/etc/group
local group database file
CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001
NOTES
The formulation given above under "RETURN VALUE" is from POSIX.1-2001.
It does not call "not found" an error, hence does not specify what value
errno
might have in this situation.
But that makes it impossible to recognize
errors.
One might argue that according to POSIX
errno
should be left unchanged if an entry is not found.
Experiments on various
Unix-like systems shows that lots of different values occur in this
situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM and probably others.
SEE ALSO
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