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NAME

     getresgid, getresuid, setresgid, setresuid -- get or set real, effective
     and saved user or group ID

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/types.h>
     #include <unistd.h>

     int
     getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid);

     int
     getresuid(uid_t *ruid, uid_t *euid, uid_t *suid);

     int
     setresgid(gid_t rgid, gid_t egid, gid_t sgid);

     int
     setresuid(uid_t ruid, uid_t euid, uid_t suid);

DESCRIPTION

     The setresuid() system call sets the real, effective and saved user IDs
     of the current process.  The analogous setresgid() sets the real,
     effective and saved group IDs.

     Privileged processes may set these IDs to arbitrary values.  Unprivileged
     processes are restricted in that each of the new IDs must match one of
     the current IDs.

     Passing -1 as an argument causes the corresponding value to remain
     unchanged.

     The getresgid() and getresuid() calls retrieve the real, effective, and
     saved group and user IDs of the current process, respectively.

RETURN VALUES

     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS

     [EPERM]            The calling process was not privileged and tried to
                        change one or more IDs to a value which was not the
                        current real ID, the current effective ID nor the
                        current saved ID.

     [EFAULT]           An address passed to getresgid() or getresuid() was
                        invalid.

SEE ALSO

     getegid(2), geteuid(2), getgid(2), getuid(2), issetugid(2), setgid(2),
     setregid(2), setreuid(2), setuid(2)

STANDARDS

     These system calls are not available on many platforms.  They exist in
     FreeBSD to support Linux binaries linked against GNU libc2.

HISTORY

     These functions first appeared in HP-UX.