CompTIA Linux+ XK0-006 (V8) Practice Question

The correct answer is 30 22 1,15 * * /usr/local/bin/backup.sh. A crontab entry has five time-and-date fields followed by the command to be run. The fields are in the order: minute, hour, day of month, month, and day of week.

• 30 specifies the 30th minute.
• 22 specifies the 22nd hour (10 PM).
• 1,15 specifies the 1st and the 15th day of the month using a list separator.
• The first * is a wildcard for the month field, meaning every month.
• The second * is a wildcard for the day of the week field, meaning any day of the week.

The entry * 22 1,15 * * /usr/local/bin/backup.sh is incorrect because the * in the minute field would cause the script to run every minute from 10:00 PM to 10:59 PM on the specified days. The entry 30 22 1-15 * * /usr/local/bin/backup.sh is incorrect because it uses a hyphen, which denotes a range, causing the script to run daily from the 1st through the 15th of the month. The entry */30 22 1,15 * * /usr/local/bin/backup.sh is incorrect because the */30 step value in the minute field would cause the job to run at 10:00 PM and 10:30 PM on the specified days.