[CentOS] Running a command at startup

Thu Dec 13 14:03:51 UTC 2018
Robert Moskowitz <rgm at htt-consult.com>

On 12/13/18 8:17 AM, Jonathan Billings wrote:
> On Wed, Dec 12, 2018 at 09:43:56PM -0500, Robert Moskowitz wrote:
>> OK....
>> I have had problems in the past with crontab parsing a command. Would I use:
>> @reboot root echo none | tee /sys/class/leds/blue\:heartbeat/trigger
>> ?
>> Or do I have to make a script and run that?
> Since this is a crontab, you can use normal shell redirection:
> @reboot root echo none > /sys/class/leds/blue\:heartbeat/trigger
> in a file in /etc/cron.d/
> The 'echo foo | sudo tee' thing is what you do for people who are
> using sudo to echo output into a file -- so often people think they
> can do 'sudo echo none > /some/path' and will be surprised it doesn't
> work.

Thanks.  This is my first encounter with 'tee'.  I guess because I 
rarely use sudo, and work in su if I need to do root things.

> I still think it makes sense to create it as a systemd unit.
Seems the better, long-term way to go, but right now I don't have time 
to learn enough about making systemd unit files.