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

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