getgrnam(3) - Linux manual page (original) (raw)
getgrnam(3) Library Functions Manual getgrnam(3)
NAME top
getgrnam, getgrnam_r, getgrgid, getgrgid_r - get group file entryLIBRARY top
Standard C library (_libc_, _-lc_)SYNOPSIS top
**#include <sys/types.h>**
**#include <grp.h>**
**struct group *getgrnam(const char ***_name_**);**
**struct group *getgrgid(gid_t** _gid_**);**
**int getgrnam_r(const char *restrict** _name_**, struct group *restrict** _grp_**,**
**char** _buf_**[restrict .**_size_**], size_t** _size_**,**
**struct group restrict** _result_**);**
**int getgrgid_r(gid_t** _gid_**, struct group *restrict** _grp_**,**
**char** _buf_**[restrict .**_size_**], size_t** _size_**,**
**struct group restrict** _result_**);**Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
**getgrnam_r**(), **getgrgid_r**():
_POSIX_C_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCEDESCRIPTION top
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 _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)](../man5/group.5.html).
The **getgrnam_r**() and **getgrgid_r**() functions obtain the same
information as **getgrnam**() and **getgrgid**(), but store the retrieved
_group_ structure in the space pointed to by _grp_. The string fields
pointed to by the members of the _group_ structure are stored in the
buffer _buf_ of size _size_. A pointer to the result (in case of
success) or NULL (in case no entry was found or an error occurred)
is stored in _*result_.
The call
sysconf(_SC_GETGR_R_SIZE_MAX)
returns either -1, without changing _[errno](../man3/errno.3.html)_, or an initial suggested
size for _buf_. (If this size is too small, the call fails with
**ERANGE**, in which case the caller can retry with a larger buffer.)RETURN VALUE top
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](../man3/errno.3.html)_ is set to indicate the
error. If one wants to check _[errno](../man3/errno.3.html)_ 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(3)](../man3/getgrent.3.html), **getgrgid**(), or
**getgrnam**(). (Do not pass the returned pointer to [free(3)](../man3/free.3.html).)
On success, **getgrnam_r**() and **getgrgid_r**() return zero, and set
_*result_ to _grp_. If no matching group record was found, these
functions return 0 and store NULL in _*result_. In case of error,
an error number is returned, and NULL is stored in _*result_.ERRORS top
**0** or **ENOENT** or **ESRCH** or **EBADF** or **EPERM** or ...
The given _name_ or _gid_ was not found.
**EINTR** A signal was caught; see [signal(7)](../man7/signal.7.html).
**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.
**ENOMEM** Insufficient memory to allocate _group_ structure.
**ERANGE** Insufficient buffer space supplied.FILES top
_/etc/group_
local group database fileATTRIBUTES top
For an explanation of the terms used in this section, see
[attributes(7)](../man7/attributes.7.html).
┌───────────────┬───────────────┬────────────────────────────────┐
│ **Interface** │ **Attribute** │ **Value** │
├───────────────┼───────────────┼────────────────────────────────┤
│ **getgrnam**() │ Thread safety │ MT-Unsafe race:grnam locale │
├───────────────┼───────────────┼────────────────────────────────┤
│ **getgrgid**() │ Thread safety │ MT-Unsafe race:grgid locale │
├───────────────┼───────────────┼────────────────────────────────┤
│ **getgrnam_r**(), │ Thread safety │ MT-Safe locale │
│ **getgrgid_r**() │ │ │
└───────────────┴───────────────┴────────────────────────────────┘VERSIONS top
The formulation given above under "RETURN VALUE" is from POSIX.1.
It does not call "not found" an error, hence does not specify what
value _[errno](../man3/errno.3.html)_ might have in this situation. But that makes it
impossible to recognize errors. One might argue that according to
POSIX _[errno](../man3/errno.3.html)_ should be left unchanged if an entry is not found.
Experiments on various UNIX-like systems show that lots of
different values occur in this situation: 0, ENOENT, EBADF, ESRCH,
EWOULDBLOCK, EPERM, and probably others.STANDARDS top
POSIX.1-2008.HISTORY top
POSIX.1-2001, SVr4, 4.3BSD.SEE ALSO top
[endgrent(3)](../man3/endgrent.3.html), [fgetgrent(3)](../man3/fgetgrent.3.html), [getgrent(3)](../man3/getgrent.3.html), [getpwnam(3)](../man3/getpwnam.3.html), [setgrent(3)](../man3/setgrent.3.html),
[group(5)](../man5/group.5.html)COLOPHON top
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man-pages@man7.orgLinux man-pages 6.10 2024-12-24 getgrnam(3)
Pages that refer to this page:getent(1), fgetgrent(3), getgrent(3), getgrent_r(3), getpwnam(3), getspnam(3), id_t(3type), group(5), nscd(8)