Cron commands to plain English(cronchecker.net)
cronchecker.net
Cron commands to plain English
http://www.cronchecker.net/
15 comments
I believe cron does not have a seconds field:
From "man 5 crontab":
From "man 5 crontab":
cron(8) examines cron entries once every minute.
The time and date fields are:
field allowed values
----- --------------
minute 0-59
hour 0-23
day of month 1-31
month 1-12 (or names, see below)
day of week 0-7 (0 or 7 is Sun, or use names)
A field may be an asterisk (*), which always stands
for "first-last".
Ranges of numbers are allowed. Ranges are two
numbers separated with a hyphen. The specified
range is inclusive.
For example, 8-11 for an "hours" entry specifies
execution at hours 8, 9, 10 and 11.
Lists are allowed. A list is a set of numbers (or
ranges) separated by commas. Examples: "1,2,5,9",
"0-4,8-12".In some uses of the CRON format there is also a seconds field at the beginning of the pattern. In that case, the CRON expression is a string comprising 6 or 7 fields.
http://en.wikipedia.org/wiki/Cron#Format
http://en.wikipedia.org/wiki/Cron#Format
[deleted]
You can also use DuckDuckGo to do this: https://duckduckgo.com/?q=cron+0+0+*+*+*+some_report.sh&t=lm
>Cron will schedule the job at this frequency: 0:00:00 on 2 Aug, 2014 0:00:00 on 3 Aug, 2014 0:00:00 on 4 Aug, 2014
Results are a little harder to read. This other site gives more natural sentences.
Results are a little harder to read. This other site gives more natural sentences.
Just played a bit with it. http://goo.gl/q8lT9B
Does not understand this syntax: "1-56/5 * * * * foo"
Sorry about that. It's a [known issue](https://github.com/pbyrne/cron-checker/issues/7).
I'd dig something going in the opposite direction! Especially packed in a shell script, e.g. `cronglish "echo testing" every half hour >> ~/.crontab`
Looks like they're the chaps behind https://deadmanssnitch.com which looks like a simple and useful service.
Hi there. Popping in to clarify that the (excellent) folks behind Dead Man's Snitch are advertising on the site, but that otherwise I'm not affiliated with them and they haven't contributed to the project beyond the ad.
That said, it's a pretty great product and you should check them out!
That said, it's a pretty great product and you should check them out!
@reboot cd ~/bin/some_daemon
is not a very good example. It will launch a shell which will change to the specified directory and then terminate. (It might produce an error message if the directory doesn't exist.)
is not a very good example. It will launch a shell which will change to the specified directory and then terminate. (It might produce an error message if the directory doesn't exist.)
I've been using http://cronwtf.github.io/ for years to double-check cron expressions.
This is nice.
I also turn to http://cronwtf.github.io when I need to sanity-check my crontab, which is a little more verbose and includes JSSpec tests.
I also turn to http://cronwtf.github.io when I need to sanity-check my crontab, which is a little more verbose and includes JSSpec tests.
Not bad,
each line in my cron has somthing lke that next to it :)
Also see crontab2english:
http://interglacial.com/pub/crontab2english.html
For visualizing a large quantity of crons, I'd recommend something akin to https://github.com/federatedmedia/cronviz which will graphically show when jobs are scheduled to run.
I built the opposite version of this, convert plain English to cron commands: http://thomseddon.github.io/cronstring
Awesome, now you have a test suite
assert(cronchecker(cronstring(input)) == input)OK, so I gave it this:
Not impressed - seems overly simplistic.
8-59/30 * * * * do_something
The command do_something will execute
the 8th through 59/30th minutes of
every hour every day.
Not impressed - seems overly simplistic.
> Not impressed - seems overly simplistic.
Agreed that it's not impressive, beings that the explanation is simply wrong. It's an edge case I'm definitely not handling properly. I've got [an open issue](https://github.com/pbyrne/cron-checker/issues/7) about combining ranges and modulo, but haven't gotten around to implementing it yet. Displaying an incorrect explanation is probably worse than no explanation, though, in retrospect.
Agreed that it's not impressive, beings that the explanation is simply wrong. It's an edge case I'm definitely not handling properly. I've got [an open issue](https://github.com/pbyrne/cron-checker/issues/7) about combining ranges and modulo, but haven't gotten around to implementing it yet. Displaying an incorrect explanation is probably worse than no explanation, though, in retrospect.
The challenge is to decide what you would want it to say in the case of, say, "14-59/15". Do you want it to list all the possibilities? That becomes tedious if you have something like 2-57/2. Do you want to try to create a more direct plain English parse?
14-59/15 - Every 15th minute starting with the 14th
up to and including the 59th.
2-57/2 - Every 2nd minutes starting with the 2nd
up to and including the 56th.
> the arcane syntax
Arcane, seriously? What kind of syntax would be modern and clear in your opinion? YAML? JSON? XML probably, with a nice 150-page XTBJSPCOSDF (Extensible Time-Based Job Scheduling for POSIX-Compatible Operating Systems Description Framework) spec? ;)
Personally, I think this is pretty straightforward:
Arcane, seriously? What kind of syntax would be modern and clear in your opinion? YAML? JSON? XML probably, with a nice 150-page XTBJSPCOSDF (Extensible Time-Based Job Scheduling for POSIX-Compatible Operating Systems Description Framework) spec? ;)
Personally, I think this is pretty straightforward:
#minute hour mday month wday command
30 1 * * * /bin/sh /etc/daily
30 3 * * 6 /bin/sh /etc/weekly
30 5 1 * * /bin/sh /etc/monthly
It would also be great to support the seconds field.