RHEL7: How to configure a rc-local service.

Presentation

With Systemd, the Init scripts are not there any more. Consequently, the execution of tasks at boot time had to change.

Hopefully, a nice solution has been found: it uses the good old rc.local file.

The Solution

Now, to execute tasks at boot time, you put them into the /etc/rc.d/rc.local file.
Then, you change the execution permissions on this file:

# chmod u+x /etc/rc.d/rc.local

Besides allowing executions of tasks, this simple operation activates the new rc-local Systemd service for all the future boots (this is like systemctl enable in Systemd language).

Finally, you can start the rc-local service and, this way, test the execution of the rc.local file:

# systemctl start rc-local

SSD optimization is a good example of such a rc-local service.

Useful Tips

In addition, Ed Greshko and several others provided several interesting ideas:

• put these lines at the beginning of the rc.local script to redirect the error messages:

  #!/bin/bash
  exec 2> /tmp/rc.local.log      # send stderr from rc.local to a log file
  exec 1>&2                      # send stdout to the same log file
  echo "rc.local started"        # show start of execution
  set -x                         # tell sh to display commands before execution

• write this line at the end of the rc.local script to prove no error stopped the execution:

  echo "rc.local completed"