Crontab MCQ Quiz - 25 Questions

Question 1 Not answered

What is cron in Linux?

A text editor used to edit configuration files A Linux scheduler service that runs commands or scripts automatically at scheduled times A package manager for installing software A command used only for checking disk space

Explanation: cron is the Linux scheduler service. It runs commands or scripts automatically based on time.

Question 2 Not answered

What does crontab mean?

Cron terminal backup Critical online table Cron table Current runtime tab

Explanation: crontab means cron table. It is where cron jobs are defined.

Question 3 Not answered

What is a cron job?

One Linux user account One package repository One mounted filesystem One scheduled command or script

Explanation: A cron job is one command or script scheduled to run at a specific time or interval.

Question 4 Not answered

Which command edits the current user's crontab?

crontab -e crontab -l crontab -r cron edit

Explanation: `crontab -e` opens the current user's crontab for editing.

Question 5 Not answered

Which command lists the current user's cron jobs?

crontab -e crontab -r crontab -l cron list-users

Explanation: `crontab -l` lists cron jobs for the current user.

Question 6 Not answered

Which command removes the current user's crontab?

crontab -l crontab -e cron remove-user crontab -r

Explanation: `crontab -r` removes the current user's crontab. Use it carefully.

Question 7 Not answered

Which command removes a crontab with confirmation?

crontab -confirm crontab -i -r crontab -safe-delete crontab -ask

Explanation: `crontab -i -r` asks for confirmation before removing the crontab.

Question 8 Not answered

Which command edits another user's crontab?

sudo crontab -u username -e crontab -e username cronuser edit username sudo cron -edit username

Explanation: With sudo/root access, `sudo crontab -u username -e` edits another user's crontab.

Question 9 Not answered

What is the correct five-field cron schedule format?

second minute hour day month command hour minute weekday month year command month day hour minute user command minute hour day-of-month month day-of-week command

Explanation: The standard user crontab format is minute, hour, day of month, month, day of week, then command.

Question 10 Not answered

What does `* * * * *` mean?

Every hour Every day at midnight Every minute Every Sunday

Explanation: Five asterisks mean every minute, every hour, every day, every month, and every weekday.

Question 11 Not answered

What does `/5 * * *` mean?

Every 5 hours Every 5 minutes Every 5 days Every Friday

Explanation: `*/5` in the minute field means every 5 minutes.

Question 12 Not answered

What does `0 * * * *` mean?

Every minute Every day at 12 PM Every month Every hour at minute 0

Explanation: `0` in the minute field and `*` in the hour field means run at the start of every hour.

Question 13 Not answered

What does `0 0 * * *` mean?

Every day at midnight Every minute Every hour Every Monday at midnight

Explanation: `0 0 * * *` means minute 0, hour 0, every day: daily at midnight.

Question 14 Not answered

What does `30 2 * * *` mean?

Every 30 minutes Every second day at 30 minutes Every day at 2:30 AM Every month at 2:30 PM only

Explanation: `30 2 * * *` runs every day at 2:30 AM.

Question 15 Not answered

What does `0 9 * * 1-5` mean?

Every day at 9 PM Every weekday at 9 AM Every 5 minutes during 9 AM Every month from January to May

Explanation: `1-5` in the day-of-week field means Monday through Friday. So it runs weekdays at 9 AM.

Question 16 Not answered

What does `0 /6 * *` mean?

Every 6 hours Every 6 minutes Every 6 days Every June

Explanation: `*/6` in the hour field means every 6 hours.

Question 17 Not answered

Which cron shortcut runs a job once when the system boots?

@startup @bootonly @systemstart @reboot

Explanation: `@reboot` runs a command once after system startup.

Question 18 Not answered

Which shortcut runs a job once per day?

@hourly @daily @weekly @reboot

Explanation: `@daily` runs a job once per day.

Question 19 Not answered

Why should you use full paths in cron jobs?

Cron only supports long filenames Cron cannot run scripts from home directories Cron has a limited environment and may not find commands or scripts Cron requires paths to start with /tmp

Explanation: Cron does not load your full interactive shell environment, so full paths make jobs more reliable.

Question 20 Not answered

Which line sets a useful PATH inside crontab?

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin PATH=automatic SET PATH ALL cron path enable

Explanation: Setting PATH inside crontab helps cron find common system commands.

Question 21 Not answered

What does `>> /var/log/backup.log 2>&1` do?

Deletes /var/log/backup.log Runs the job twice Sends output only to the screen Appends output and errors to /var/log/backup.log

Explanation: `>>` appends standard output, and `2>&1` sends standard error to the same place.

Question 22 Not answered

What does `MAILTO=""` do in crontab?

Deletes the mail service Sends mail to root only Disables cron email output Creates a new mailbox

Explanation: `MAILTO=""` disables cron mail output for jobs in that crontab.

Question 23 Not answered

What is the key difference between user crontab and `/etc/crontab`?

User crontab includes seconds; /etc/crontab does not /etc/crontab includes a username field; user crontab does not /etc/crontab cannot run commands User crontab is only for root

Explanation: System crontab `/etc/crontab` has an extra user field to specify which user runs the command.

Question 24 Not answered

Which command checks cron logs on Ubuntu/Debian?

grep CRON /var/log/syslog grep CRON /var/log/cron cat /etc/crontab/log cron --logs

Explanation: On Ubuntu/Debian, cron entries are commonly found in `/var/log/syslog`.

Question 25 Not answered

Which command helps prevent overlapping cron jobs?

grep chmod flock pwd

Explanation: `flock` can use a lock file so a new cron run does not start if the previous one is still running.

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