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 supe‐
       ruser, 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 fea‐
       ture.   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
       EINVAL The group ID specified in gid is not valid in this user namespace.

       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 variation across kernel versions.

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

COLOPHON
       This  page  is  part of release 3.74 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at http://www.kernel.org/doc/man-pages/.



Linux                                       2014-09-21                                  SETGID(2)