getgrnam, getgrnam_r, getgrgid, getgrgid_r — get group file entry
#include <sys/types.h> #include <grp.h>
struct group *getgrnam( |
const char * | name); |
struct group *getgrgid( |
gid_t | gid); |
int
getgrnam_r( |
const char * | name, |
| struct group * | gbuf, | |
| char * | buf, | |
| size_t | buflen, | |
| struct group ** | gbufp); |
int
getgrgid_r( |
gid_t | gid, |
| struct group * | gbuf, | |
| char * | buf, | |
| size_t | buflen, | |
| struct group ** | gbufp); |
The 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 /etc/group, NIS, and
LDAP) that matches the group name name.
The 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 gid.
The getgrnam_r() and
getgrgid_r() functions obtain
the same information, but store the retrieved group structure in the space pointed to
by gbuf. This
group structure contains
pointers to strings, and these strings are stored in the
buffer buf of size
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;char * gr_passwd;gid_t gr_gid;char ** gr_mem;};
The maximum needed size for buf can be found using
sysconf(3) with the
_SC_GETGR_R_SIZE_MAX
parameter.
The getgrnam() and
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), getgrgid(), or getgrnam().
The getgrnam_r() and
getgrgid_r() functions return
zero on success. In case of error, an error number is
returned.
0 or
ENOENT or ESRCH or EBADF or EPERM or ...The given name or gid was not found.
A signal was caught.
I/O error.
The maximum number (OPEN_MAX) of files was open already
in the calling process.
The maximum number of files was open already in the system.
Insufficient memory to allocate group structure.
Insufficient buffer space supplied.
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.
This page is part of release 2.79 of the Linux man-pages project. A
description of the project, and information about reporting
bugs, can be found at
http://www.kernel.org/doc/man-pages/.
|
Copyright 1993 David Metcalfe (davidprism.demon.co.uk) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. References consulted: Linux libc source code Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) 386BSD man pages Modified 1993-07-24 by Rik Faith (faithcs.unc.edu) Modified 2003-11-15 by aeb |