--- Process.getpriority(which, who)

    ץץ롼ס桼θߤΥץ饤ƥ
    ޤ(getpriority(2) [manual page] )

    Process ⥸塼 which ȤƻǤ 
    PRIO_PROCESS, PRIO_PGRP,
    PRIO_USER Ƥޤ

    who ˤϡwhich ͤˤäƥץ IDץ
    롼 ID桼 ID Τ줫ꤷޤ

    ץ饤ƥμ˼Ԥϡ㳰 Errno::EXXX ȯ
    ޤ

