Cannot get cron to work on Amazon EC2?

Question

I've spent two days trying to understand why I can not get cron to work on my Ubuntu EC2 instance. I've read the documentation. Can anyone help? All I want is to get a working cronjob.

I am using a simple wget command to test cron. I have verified that this works manually from the command line:

/usr/bin/wget -O /home/ubuntu/backups/testfile http://www.nytimes.com/

My crontab file looks like this:

02 * * * * /usr/bin/wget -O /home/ubuntu/backups/testfile http://www.nytimes.com/

I have single spaces between the commands and I have a blank line below the command. I've also tried to execute this command from the system level sudo crontab -e. It still doesn't work.

The cron daemon is running:

ps aux | grep crond                                                                                                                    ubuntu    2526  0.0  0.1   8096   928 pts/4    S+   10:37   0:00 grep crond 

The cronjob appear to be running:

$ crontab -l 02 * * * * /usr/bin/wget -O /home/ubuntu/backups/testfile http://www.nytimes.com/ 

Does anyone have any advice or possible solutions?

Thanks for your time.

Answer 1

Cron can be run in Amazon-based linux server just like in any other linux server.

1. Login to console with SSH.
2. Run crontab -e on the command line.
3. You are now inside a vi editor of the crontab of the current user (which is by default the console user, with root permissions)
4. To test cron, add the following line: * * * * * /usr/bin/uptime > /tmp/uptime
5. Now save the file and exit vi (press Esc and enter :wq).
6. After a minute or two, check that the uptime file was created in /tmp (cat /tmp/uptime).
7. Compare it with the current system uptime by typing the uptime command on the command line.

The scenario above worked successfully on a server with the Amazon Linux O/S installed, but it should work on other linux boxes as well. This modifies the crontab of the current user, without touching the system's crontabs and doesn't require the user inside the crontab entry, since you are running things under your own user. Easier, and safer!

Answer 2

Your cron daemon is not running. When you're running ps aux | grep crond the result is showing that only the grep command is running. Be aware of this whenever you run ps aux | grep blah.

Check the status of the cron service by running this command.

Try:

sudo service crond status 

Additional information here: http://www.cyberciti.biz/faq/howto-linux-unix-start-restart-cron/.