单项选择题 An operator is asked to verify the exact location of the default JRE binary. The following commands were run: $ which java /usr/bin/java $ ls -l /usr/bin/java lrwxrwxrwx 1 root other 23 Jan 27 2006 /usr/bin/java -> ../jre1.5.0_06/bin/java Based on the command outputs above, what is the path to the java executable file?（）

单项选择题 What command would an operator use to move a file from the /old_dir directory to the /new_dir directory without changing the file name?（）

单项选择题 Which of the following commands will show the users that are logged on a system ?（）