where does Cron look for the default mail binary?

Question

I have setup Cron Jobs to run inside a Chroot Environment, depending on the User/Group;

I have noticed that these cron jobs, running inside the chroot environment, fail to send any mail.

Log files report that it cannot find a program to send mail.

Where does the Cron process look for the default mail binary? Can you set or configure this path?

and on a side note.. if the MAILTO= variable is not set, how does Cron know where to send mail to? does it just send mail to the user running the job, on the local host?

thanks!

Answer 1

Where does the Cron process look for the default mail binary?

Unless otherwise specified I'm fairly sure it just uses the mail program it finds in the path (/bin:/usr/bin). You can though specify the -m command line argument for some versions of cron

-m This option allows you to specify a shell command string to use for sending cron mail output instead of sendmail(8). This com- mand must accept a fully formatted mail message (with headers) on stdin and send it as a mail message to the recipients speci- fied in the mail headers.

The above works on CentOS/RHEL, Ubuntu looks different

Can you set or configure this path?

See above.

if the MAILTO= variable is not set...

If MAILTO is not set then as you suspect the mail is delivered to the local user who is running the job.

On CentOS/RHEL you can specify extra command line arguments in /etc/sysconfig/crond so that you dont't have to edit your init scripts. Other OS/distros may provide similar functionality.