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 variation across kernel versions.

SEE ALSO

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

COLOPHON

       This  page  is  part of release 3.54 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/.