Cron and at

Question 1

Crontab file

Answer 1

/etc/crontab

• minute (0-59)
• hour (0-23)
• day of month (1-31)
• month (1-12) or jan,feb,mar
• day of week (0-6) or sun,mon…
• user-name
• command to be executed

Question 2

Set up cron job

Answer 2

crontab -e
*/2 4 * * * /usr/bin/tar -czf myfile.tar.gz /home/user/important_ file1

Question 3

List cron jobs

Answer 3

crontab -l

crontab -l -u kenny

Question 4

Location of where cron job will be saved

Answer 4

/var/spool/cron/user_name_run_crontab -e

Question 5

Remove crontab jobs

Answer 5

crontab -r -u kenny

Question 6

Location of dirs where scripts could be run on a regular basis as if they were cron jobs

Answer 6

/etc/cron.hourly/
/etc/cron.dailly/
/etc/cron.weekly/
/etc/cron.monthly/

Question 7

Dir contains cron scripts for entire system

Answer 7

/etc/cron.d/

Question 8

Forbid users to create cron jobs

Answer 8

/etc/cron.deny

Question 9

Create job with at

Answer 9

at now + 5 minutes
enter command
press ctrl+d

at 4:00 AM tomorrow
at -f /home/user/script.sh 10:00 AM Oct 8 2018

Question 10

List at queue

Answer 10

atq

Question 11

Remove schedule at’s job

Answer 11

atrm [job number]

Question 12

Allow/ Deny users to run schedule a job with at

Answer 12

vim /etc/at.allow
add root to allow root to schedule at jobs
vim /etc/at.deny
add user to deny user to schedule at jobs