Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

RedHat 9 (Linux i386) - man page for setgid (redhat section 2)

SETGID(2)						     Linux Programmer's Manual							 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 current process. If the caller is the superuser, the real and saved group ID's are also set. Under Linux, setgid is implemented like the POSIX version with the _POSIX_SAVED_IDS feature. This allows a setgid program that is not suid root to drop all of its group privileges, do some un-privileged work, and then re-engage the original effective group ID in a secure man- ner.
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
ERRORS
EPERM The user is not the super-user (does not have the CAP_SETGID capability), and gid does not match the effective group ID or saved set-group-ID of the calling process.
CONFORMING TO
SVr4, SVID.
SEE ALSO
getgid(2), setregid(2), setegid(2) Linux 2.5 2002-03-09 SETGID(2)