5.2 Cron and Scheduled Jobs

Question 1

A _________ is a script or command designated to run at periodic predetermined intervals.

Answer 1

A cron job is a script or command designated to run at periodic predetermined intervals.

Question 2

What is a daemon?

Answer 2

A daemon is a computer program that runs as a background process, rather than being directly controlled by an interactive user.

Question 3

What is Cron?

Answer 3

cron is a robust task scheduler that allows users to schedule repetitive tasks to run on a regular basis.

Question 4

____________are often started at boot up. While other

____________ respond to network requests and hardware activity, cron is initiated at designated time intervals.

Answer 4

Daemons are often started at boot up. While other
daemons respond to network requests and hardware
activity, cron is initiated at designated time intervals.

Question 5

Tasks are stored and scheduled in a file called a ___________.

Answer 5

Tasks are stored and scheduled in a file called a crontab (cron table).

• Each user has their own individual, private crontab.
• System crontabs for system level actions.
• Tasks scheduled by users. are run under that user’s privilege level.
• Root users can have a crontab too.

Question 6

Crontabs come in two varieties. What are they?

Answer 6

• User-level: runs for a specific user under their privilege level.
• System-level: runs for the system as a whole under root privileges.

Question 7

What is the general syntax for a crontab?

Answer 7

minute hour day-of-month month day-of-week command

Question 8

What goes in this directory?

/etc/cron/d

Answer 8

custom cron jobs

Question 9

Lynis is a security scanner used to ____________________.

Answer 9

Lynis is a security scanner used to check a machine for vulnerabilities.

• Generates and saves reports of its findings for administrators to review.
• Offers numerous scan types.

Question 10

• When will the following cron schedules run?*/10 * * * *

Answer 10

At every 10th minute.

Question 11

• What event is the following cron a minute away from?

59 23 31 12 *

Answer 11

New years

Question 12

What do the following hypothetical cron likely do?

0 18 * * 1-5 /home/Bob/Sales/sum_of_sales.sh

Answer 12

1. Run a script that adds up all the sales for the work day.

2. A weekly automated system upate.

Question 13

What is a shebang?

Answer 13

Is the commented file declaration at the top of a shell script.

Question 14

Is the .sh extension needed for shell scripts?

Answer 14

Nope! As long as the shebang is there, the file should be able to run as a script!

Question 15

What two characters should come before the filename of a script?

Answer 15

./

Question 16

Jane’s script has user and group ownership of a script with -rw-r--r-- permissions, but she cannot get it to run. What must she do to the file before it will run?

Answer 16

Run chmod +x on her file!

Question 17

How does the -x option modify the tar command?

Answer 17

This option will let tar extract an archive!

Question 18

If a directory has ten files and the following command is used in it, how many files are being archived?

tar cvvWf backups/archive.tar

Answer 18

Zero, because tar doesn’t compress!! But all files should be archived as they’re all in ., the current directory!

Question 19

What option prints the full file specification of files as you interact with them?

Answer 19

-vv

Question 20

Why is the -f option used in almost every tar operation?

Answer 20

The -f option lets you designate a tar file to either create or extract or list from.