setgid(2) [redhat man page]

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)

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 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.

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 3.25 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								    2009-10-17								 SETGID(2)