Unix for Beginners
Unix Shell Programming
Advanced Unix
Unix Useful References
Unix Useful Resources
Selected Reading
Copyright © 2014 by tutorialspoint
|
getgroups() - Unix, Linux System Call
Advertisements
NAME
getgroups, setgroups - get/set list of supplementary group IDs
SYNOPSIS
#include <sys/types.h>
#include <unistd.h>
int getgroups(int size, gid_t list[]);
#include <grp.h>
int setgroups(size_t size, const gid_t *list); DESCRIPTION
Tag | Description |
getgroups() | |
Up to
size supplementary group IDs (of the calling process) are returned in
list. It is unspecified whether the effective group ID of the calling process
is included in the returned list. (Thus, an application should also call
getegid(2)
and add or remove the resulting value.)
If
size is zero,
list is not modified, but the total number of supplementary group IDs for the
process is returned.
|
setgroups() | |
Sets the supplementary group IDs for the process.
Appropriate privileges (Linux: the
CAP_SETGID capability) are required.
|
RETURN VALUE
Tag | Description |
getgroups() | |
On success, the number of supplementary group IDs is returned.
On error, -1 is returned, and
errno is set appropriately.
|
setgroups() | |
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
|
ERRORS
Tag | Description |
EFAULT |
list has an invalid address.
|
EINVAL |
For
setgroups(), size is greater than
NGROUPS (32 for Linux 2.0.32).
For
getgroups(), size is less than the number of supplementary group IDs, but is not zero.
|
EPERM |
The calling process has insufficient privilege to call
setgroups(). |
NOTES
A process can have up to at least NGROUPS_MAX supplementary group IDs
in addition to the effective group ID. The set of supplementary group IDs
is inherited from the parent process and may be changed using
setgroups(). The maximum number of supplementary group IDs can be found using
sysconf(3):
long ngroups_max;
ngroups_max = sysconf(_SC_NGROUPS_MAX);
|
The maximal return value of
getgroups() cannot be larger than one more than the value obtained this way.
The prototype for
setgroups() is only available if
_BSD_SOURCE is defined.
CONFORMING TO
SVr4, 4.3BSD.
The
getgroups() function is in POSIX.1-2001.
Since
setgroups() requires privilege, it is not covered by POSIX.1-2001.
SEE ALSO
Advertisements
|
|
|
To Continue Learning Please Login
Login with Google