CentOS - Dec 2018 - Running a command at startup

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...
>
>
> Leroy Tennison
> Network Information/Cyber Security Specialist
> E: leroy at datavoiceint.com
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> ________________________________________
> From: CentOS <centos-bounces at centos.org> on behalf of Robert
Moskowitz <rgm at htt-consult.com>
> Sent: Wednesday, December 12, 2018 6:04 PM
> To: CentOS mailing list
> Subject: [EXTERNAL] [CentOS] Running a command at startup
>
> On a support forum, I was told that to turn off my board's blue led
run:
>
> echo none | sudo tee /sys/class/leds/blue\:heartbeat/trigger
>
> Well, this does not survive a system reboot.  So I was told:
>
> Add the off bit to
>
>       /etc/rc.local
>
> Add it above "exit 0"
>
> So of course, CentOS is past using rc.local and recommends:
>
> # It is highly advisable to create own systemd services or udev rules
> # to run scripts during boot instead of using this fi
>
> So can someone point me to how to make this into a simple systemd service?
>
> thanks
>
>
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> 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.

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