|| Linux Programmer's Manual
NAME setgid - set group identity
() sets the effective group ID of the calling process. If the caller is the superuser, the real GID and saved set-group-ID are also set.
() is implemented like the POSIX version with the
feature. This allows a set-group-ID program that is not set-user-ID-root to drop all of its group privileges, do some un-privileged work, and then reengage the original effective group ID in a secure manner.
RETURN VALUE On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
The calling process is not privileged (does not have the
CAP_SETGID capability), and
gid does not match the real group ID or saved set-group-ID of the calling process.
CONFORMING TO SVr4, POSIX.1-2001.
NOTES The original Linux
setgid() system call supported only 16-bit group IDs. Subsequently, Linux 2.4 added
setgid32() supporting 32-bit IDs. The glibc
setgid() wrapper function transparently deals with the variation across kernel versions.
COLOPHON This page is part of release 3.53 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/.