table of contents
- wheezy 3.44-1
- jessie 3.74-1
- jessie-backports 4.10-2~bpo8+1
- testing 4.10-2
- unstable 4.10-2
|GETGROUPS(2)||Linux Programmer's Manual||GETGROUPS(2)|
NAME¶getgroups, setgroups - get/set list of supplementary group IDs
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
DESCRIPTION¶getgroups() returns the supplementary group IDs of the calling process in list. The argument size should be set to the maximum number of items that can be stored in the buffer pointed to by list. If the calling process is a member of more than size supplementary groups, then an error results. 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.)
RETURN VALUE¶On success, getgroups() returns the number of supplementary group IDs. On error, -1 is returned, and errno is set appropriately.
- list has an invalid address.
- size is less than the number of supplementary group IDs, but is not zero.
- size is greater than NGROUPS_MAX (32 before Linux 2.6.4; 65536 since Linux 2.6.4).
- Out of memory.
- The calling process has insufficient privilege.
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 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 preserved across an execve(2).
long ngroups_max; ngroups_max = sysconf(_SC_NGROUPS_MAX);The maximum return value of getgroups() cannot be larger than one more than this value.
SEE ALSO¶getgid(2), setgid(2), getgrouplist(3), initgroups(3), capabilities(7), credentials(7)
COLOPHON¶This page is part of release 3.44 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/.