A program is usually run under the UID of the person who executes it (emacs, gcc, vi) except those that need to do special things (passwd, chsh) that are run as setUID root.

• 程序通常在执行该程序（emacs, gcc, vi)的用户UID下运行，除非该程序需要通过设置根用户UID（即SetUID）来运行一些特定的任务（passwd, chsh）。