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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.