CIT 174

Week 6
Chapter 6 Review Questions
1. The command ps –A xo comm displays the following information (d) all processes running on the system, including those with no controlling terminal, with the command-line field displayed for each one.
2. The (a) TIME field in the ps command output defines how much cumulative CPU time a process has used since it was started.
3. The CMDLINE files of the ps command output displays (b) the command line used to start the process shown on each line.
4. Which of the following commands is invalid if run by a regular user? (a) renice -10 1035.
5. Which of these programs does not allow you to change the nice level of a running process? (b) free.
6. To update the process data displayed by the top command, you press which key? (b) spacebar.
7. Dynamically linked applications are preferred for their better memory usage unless (c) the necessary libraries to run the application are not installed on the Linux system.
8. Thrashing occurs when (a) an excessive amount of information is moved to and from the swap partition in a short time.
9. The command “vmstat 4” does which of the following? (c) displays continuous updates of the virtual memory status on a new line every four seconds.
10. How can you switch between multiple virtual consoles in text and graphical
environments? By using the Ctrl+Alt+F2 key combination.F2 to F6 are available for virtual consoles. While the graphical interface (X) runs on F7.
11. Describe at least four fields of information provided by the command “ps auxf”. The PID is the process ID, the command field tells what command began the process, the %CPU tells how much time and memory are being used by the process, and the state of the process.
12. By starting multiple jobs form one shell, you can (c) manage those jobs with the jobs, bg and fg commands.
13. Briefly explain the difference in time specification formats for the “at” and “crontab” commands. The “at” command allows you do execute a command in the future. The “crontab” command allows you to execute commands repeatedly in the future at regular intervals.
14. The background processes that manage commands submitted using at and cron are (c) atd and crond.
15. When using the at command interactively to enter commands scheduled for future execution, you indicate that you have finished entering commands by pressing (a) Clrt+d.
16. The batch command is used to schedule jobs so that (c) the system will not be overloaded with scheduled tasks.
17. A simple method for root to schedule recurring systems administrations tasks is to (b) add a script to a directory shuch as /etc/cron.daily or /etc/cron.weekly.
18. The output of a “cron” job is normally sent via email to the user who submitted the “cron” job or to the user defined by the MAILTO variable within the file containing the “cron” job.
19. Name, in order form left to right, the fields of the “crontab” time specifications, giving the range of valid numeric values for each one. Minute of the hour (0-59), Hour of the day (0-23), Day of the month (0-32), Month of the year (0-12), Day of the week (0-7).
20. Output from a command executed as part of a new “cron” job cannot be redirected to a file using standard redirection operators because the environment in which the “cron” job was created is likely to exist when the job is executed. False.
21. The /etc/cron.deny file can include a user name in order to deny that user access to the “crontab” command.
22. Name the two separate commands that can be used instead of at –l and at –d. The alternate commands for list are atq (or at –l)and for delete atrm (or at –d).
23. All processes in Linux, except the init process (PID1) are created (b) when another process forks.
24. A zombie process is one that (d) is no longer in existence, though the Linux kernel still maintains information as if it were.
25. Describe why you should try SIGTERM before using SIGKILL. SIGTERM is better because the process shuts down and saves the work in progress. Unlike SIGKILL which simply pulls the plug on the process.