[CentOS] Running a command at startup

[Robert Moskowitz]

On 12/12/18 9:17 PM, Richard wrote:
>
>> Date: Wednesday, December 12, 2018 20:25:48 -0500
>> From: Robert Moskowitz <rgm at htt-consult.com>
>>
>>
>> On 12/12/18 7:11 PM, Leroy Tennison wrote:
>>> Does your version of CentOS have the @reboot crontab option?  If
>>> it does this is probably easier unless you want to learn how to
>>> write systemd files.
>> CentOS 7.6.  I will have to google @reboot...
>
> see: man -S5 crontab  -- the "extensions" section.
>

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?

thanks