SETGID(2)

NAME
setgid - set group identity

SYNOPSIS
#include <sys/types.h>
#include <unistd.h>

int setgid(gid_t gid);

DESCRIPTION
setgid() 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. Under Linux, setgid() is implemented like the POSIX version with the _POSIX_SAVED_IDS 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.

ERRORS

EPERM
    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.

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.

CONFORMING TO
SVr4, POSIX.1-2001.

SEE ALSO
getgid(2), setegid(2), setregid(2), capabilities(7), credentials(7)

COLOPHON
This page is part of release 3.41 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/.