How to execute a command at system startup

[hanzer]

My FreeBSD system needs to execute a couple simple commands sometime during or shortly after the boot process. After a bit of searching, it seems many people have this need and there doesn't seem to be a canonical solution. There is much written about managing services (daemons) but learning the details of rc.d scripting in order to execute a command (# camcontrol apm 0:0:0 -l 250) seems like [s]a dirty[/s] an absurd hack. The rc man page says:

The rc.local script contains
commands which are pertinent only to a specific site. Typically, the
/usr/local/etc/rc.d/ mechanism is used instead of rc.local these days but
if you want to use rc.local, it is still supported. In this case, it
should source /etc/rc.conf and contain additional custom startup code for
your system. The best way to handle rc.local, however, is to separate it
out into rc.d/ style scripts and place them under /usr/local/etc/rc.d/.

This is the only information I could find about /etc/rc.local (was this vague, sentimental man page blurb written by a child?). If anyone here is familiar with rc.local syntax and its use within the FreeBSD rc system, if you could post a simple, best practices example of a working script, that would be very helpful!

[J65nko]

You can create a crontab entry with the "@reboot" time/period specifier. From crontab(5) :

Instead of the first five fields, a line may start with `@' symbol fol-
 lowed either by one of eight special strings or by a numeric value.  The
 recognized special	strings are:

	   string	   meaning
	   ------	   -------
	   @reboot	   Run once, at	startup	of cron.

You can create a simple shell script that runs/executes whatever you want to run at reboot,

Please keep in mind that your script runs with a very limited subset of environment settings like PATH.
From the shell execute which env and enter the results in your first iteration of the script, The resulting output of the script will be mailed locally. Inspect that mail to see the environment settings.

[hanzer]

Thanks for suggesting the workaround. I did this:

$ sudo crontab -u root -e

@reboot /sbin/camcontrol apm 0:0:0 -l 250
@reboot /sbin/camcontrol apm 1:0:0 -l 250

The machine is too busy to test it...