huschi.net

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.
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 varia-
       tion across kernel versions.
SEE ALSO
       getgid(2), setegid(2), setregid(2), capabilities(7), credentials(7)
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/.

Linux                             2010-11-22                         SETGID(2)