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); |
![[Note]](../stylesheet/note.png) |
Note | ||
|---|---|---|---|
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DESCRIPTION
getgroups()-
Up to
sizesupplementary group IDs (of the calling process) are returned inlist. 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.) Ifsizeis zero,listis 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_SETGIDcapability) are required.
RETURN VALUE
getgroups()-
On success, the number of supplementary group IDs is returned. On error, −1 is returned, and
errnois set appropriately. setgroups()-
On success, zero is returned. On error, −1 is returned, and
errnois set appropriately.
ERRORS
- EFAULT
-
listhas an invalid address. - EINVAL
-
For
setgroups(),sizeis greater thanNGROUPS(32 for Linux 2.0.32). Forgetgroups(),sizeis less than the number of supplementary group IDs, but is not zero. - EPERM
-
The calling process has insufficient privilege to call
setgroups().
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.
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.