写一个脚本文件checkuser,该脚本运行时带一个用户名作为参数，具体要求如下： 1)如果命令行格式不符合要求，应有错误提示信息； 2)在/etc/p...

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写一个脚本文件checkuser,该脚本运行时带一个用户名作为参数，具体要求如下： 1)如果命令行格式不符合要求，应有错误提示信息； 2)在/etc/passwd文件中查找是否有该用户， 如有，则输出“Found in the /etc/passwd file.” 否则，输出“No such on our system” -Write a script file checkuser, the script run-time with a user name as a parameter, and specific requirements are as follows: 1) If the command-line format does not meet the requirements, there should be error message 2) in/etc/passwd file to check if there were any users, and if so, then the output " Found in the/etc/passwd file. " Otherwise, output" No such on our system "