1. # 实时显示系统使用情况总结和进程等
    2. top
    4. # 杀死某个进程
    5. # kPID[ENTER]SIGNAL # PID: 进程id；SIGNAL：15/SIGTERM/sigterm,9/SIGKILL/sigkill
    7. # Fields 管理
    8. # f # 出现字段管理（Window 1:Def, Window 2:Job, Window 3:MEM, Window 4:USR; 按 a 切换）
    10. # x # toggle bolding of the sorted column
    11. # y # toggle bolding of running processes
    13. # u/U # filter user
    15. # o  # filter other field
    16.          # [!]FIELD?VALUE
    17.          # ?: = > <
    19. # r  # r PID NICENESS
    21. ### BEGIN: 进程优先级
    22. # PRI(new) = PRI(old) + NI
    23. # NI = {-20, 19}
    25. # 设置进程优先级
    26. sudo nice -n 19 tar -czvf compressed_filename.tgz dir_name
    28. # 修改进程优先级
    29. sudo renice 19 -p 20136
    30. sudo renice -20 -u mysql
    31. sudo renice -20 -g website
    32. ### END: 进程优先级
    34. ### BEGIN: 磁盘访问优先级
    35. sudo ionice -c3 -p24351 # -c: class, Real Time(1), Best Effort(2), Idle(3)
    36. ### END:   磁盘访问优先级