I'm sure there is a "cron" option that uses the "@reboot" specification, thus allowing one-off script execution.
Looking at the output of "man 5 crontab", I see the following under the "EXTENSIONS" heading --
EXTENSIONS
When specifying day of week, both day 0 and day 7 will be considered Sunday. BSD and ATT seem to disagree about this.
Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would be rejected by ATT or BSD cron -- they want to see "1-3"
or "7,8,9" ONLY.
Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9".
Names of months or days of the week can be specified by name.
Environment variables can be set in the crontab. In BSD or ATT, the environment handed to child processes is basically the one from
/etc/rc.
Command output is mailed to the crontab owner (BSD can’t do this), can be mailed to a person other than the crontab owner (SysV can’t
do this), or the feature can be turned off and no mail will be sent at all (SysV can’t do this either).
These special time specification "nicknames" are supported, which replace the 5 initial time and date fields, and are prefixed by the
’@’ character:
@reboot : Run once after reboot.
@yearly : Run once a year, ie. "0 0 1 1 *".
@annually : Run once a year, ie. "0 0 1 1 *".
@monthly : Run once a month, ie. "0 0 1 * *".
@weekly : Run once a week, ie. "0 0 * * 0".
@daily : Run once a day, ie. "0 0 * * *".
@hourly : Run once an hour, ie. "0 * * * *".