Following a system boot， the display indicates that previously detected hardware is missing. What command should be used to identify the missing hardware？（）

Asystem’sbackupsarefailing.Errorloganalysisindicatestha...

单项选择题A system’s backups are failing. Error log analysis indicates that there is either a hardware or media problem. Which command is used to determine if there is a hardware problem with the tape drive？（）

Asystemadministratorwouldliketoverifytheuserdefinitions...

单项选择题A system administrator would like to verify the user definitions in the /etc/passwd file. Which of the following commands will accomplish this？（）

Asystemadministratorhasbeenaskedtolockaspecificloginacc...

单项选择题A system administrator has been asked to lock a specific login account. Which of the following commands is used to accomplish this？（）