GETGID(2) Linux Programmers Manual GETGID(2)
getgid, getegid - get group identity
getgid() returns the real group ID of the calling process.
getegid() returns the effective group ID of the calling process.
When a normal program is executed, the effective and real group ID of
the process are set to the group ID of the user executing the file.
When a set ID program is executed the real group ID is set to the group
of the calling user and the effective user ID corresponds to the set
group ID bit on the file being executed.
These functions are always successful.
getresgid(2), setgid(2), setregid(2), credentials(7)
This page is part of release 3.05 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/.
Linux 1993-07-23 GETGID(2)