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？（）

Auserwouldliketheirshellprompttoreflectthecurrentdirect...

单项选择题A user would like their shell prompt to reflect the current directory. Which of the following environment variables can be set to accomplish this？（）