单项选择题 The operator needs to execute a long-running shell script. How can the script be executed so the operator does not have to wait until it is complete to access the command prompt?（）

单项选择题 An operator needs to transfer several files in the same directory using ftp without being prompted. Which of the following ftp subcommands must be used?（）

单项选择题 What is the default configuration file used by the sendmail command?（）