Introduction - If you have any usage issues, please Google them yourself
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 <user> in the/etc/passwd file. " Otherwise, output" No such <user> on our system "