在UNIX系统中，Shell程序(21)实现显示用户主目录以及当前命令的进程标识符。

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Software　quality　assurance　is　now　an(71)sub-discipline　of　software　engineering.　As　Bucldy　and　Oston　point　out,(72)software　quality　assurance　is　likely　to　lead　to　an　ultimate(73)of　software　costs.　However,　the　major　hurdle　in　the　path　of　software　management　in　this　area　is　the　lack　of(74)software　standards.　The　development　of　accepted　and　generally　applicable　standards　should　be　one　of　the　principal　goals　of(75)in　software　engineering.

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