=======================================
freebsd crontab syntax
=======================================

=======================================
six fields
---------------------------------------

# * * * * * command
# minute hour day_of_month month day_of_week command

# minute       : 0-59
# hour         : 0-23
# day_of_month : 1-31
# month        : 1-12
# day_of_week  : 0-7 (0=sunday, 7=sunday)

# 0            : value
# *            : any
# ,            : list separator
# -            : range
# /            : every nth (*/2=every other, 1-23/2=every odd in range, 0-22/2=every even in range, */5=every 5th)

*/2  * * * *   : 0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58
*/5  * * * *   : 0,5,10,15,20,25,30,35,40,45,50,55
*/10 * * * *   : 0,10,20,30,40,50,60
*/15 * * * *   : 0,15,30,45
*/20 * * * *   : 0,20,40
*/30 * * * *   : 0,30


=======================================
two fields
---------------------------------------

@reboot        : after reboot
@every_second  : @1
@every_minute  : * * * * *
@hourly        : 0 * * * *
@daily         : 0 0 * * *
@midnight      : 0 0 * * *
@weekly        : 0 0 * * 0
@monthly       : 0 0 1 * *
@yearly        : 0 0 1 1 *
@annually      : 0 0 1 1 *


=======================================
seconds from time of reload
---------------------------------------

The `@' symbol followed by a numeric value has a	special	notion of run-
ning a job that many seconds AFTER COMPLETION of	the  previous  invoca-
tion  of	 the job.  Unlike regular syntax, it guarantees	not to overlap
two or more invocations of the same job during normal  cron  execution.
Note,  however,	that  overlap may occur	if the job is running when the
file containing the job is modified  and	 subsequently  reloaded.   The
first  run  is scheduled	for the	specified number of seconds after cron
is started or the crontab entry is reloaded.

@1           : every 1 second
@60          : every 1 minute
@5400        : every 90 minutes


=======================================
end
=======================================