
Cron Job Run Time Predictor - Golden201
https://cronjob.xyz/
======
tyingq
Maybe an example of what you consider a valid cron expression would help.
Pasted things straight out of crontab, with and without the command part, and
it says "invalid cron expression" for all of them.

Edit: Apparently, you're being strict about only a single space between
fields, and not including the command part.

~~~
majewsky
It apparently just wants the timing information, and will print a readable
schedule based on that. Try

    
    
      0 */2 * * *
    

By the way, this app sorely needs a link-to-result functionality.

~~~
tyingq
My crontab had extra spaces and/or tabs between fields, which crontab(5) is
fine with. This app wants only a single space between fields.

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xori
[https://crontab.guru](https://crontab.guru)

~~~
aargh_aargh
Indeed, I find this one much more useful and use it often. It gives you a
compact description of the expression in words, e.g.:

    
    
      “At every 5th minute.”
      “At 03:20 on Sunday.”
      “At every 10th minute past hour 3 and 4.”

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jordanrobinson
There are quite a few of these about on the internet, they make a nice little
pet project if you're trying to pick up a language or methodology.

Full disclaimer: I made one as a toy a while ago
([http://whenwillcronfire.jordanrobinson.co.uk/](http://whenwillcronfire.jordanrobinson.co.uk/))
but never really did anything with it.

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egwynn
I’ve long wanted API access to a system’s cron “smarts”. Like I sort of wish
/usr/sbin/cron was a “dumb shell” around a hypothetical "/usr/lib/libcron.so",
so that I could write programs that could just get _the exact right answer_
(about timing, syntax, etc.) without having to guess. Does that exist?

~~~
IshKebab
I think systemd timers may provide something like that but everyone seems to
be against systemd because it tries to do things correctly. Shonky text-based
configuration files and fragile integration is clearly better.

~~~
CaptSpify
> against systemd because it tries to do things correctly.

There are good sides to systemd, _and_ bad sides. Pretending the issue is one-
sided like this is naive at best.

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dsr_
[https://github.com/alpaker/cronviz](https://github.com/alpaker/cronviz) is a
graphic visualizer of a whole crontab, and it runs locally so you don't need
to offer your info to a random website.

(I'm not associated with it in any way; I just had a need for it a few weeks
ago.)

~~~
noxToken
> _it runs locally so you don 't need to offer your info to a random website_

Odd reasoning for this specific instance. The only thing to offer the website
is a cron expression. Without any context, how sensitive is that information?

~~~
dsr_
Context makes it much more valuable. If you only had one cron expression, you
would just figure it out by yourself. The interesting things happen when
you've got fifty cron jobs running on six boxes (or five thousand on six
hundred) and you want to see when things get slammed. Having the name of the
job associated with the colorful blips is important.

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sandipp
crashed your site, got the following error- " Fatal error: Maximum execution
time of 30 seconds exceeded in
/home/cronjob/public_html/application/models/Cron/AbstractField.php on line 97
" Sanitize the inputs. I used this invalid expression - * 5/* * * _

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WrtCdEvrydy
Also, cron supports 6 asterisk for running cron jobs down to a second.

~~~
dozzie
Uhm... No? Depends on what cron implementation you use, but neither Vixie cron
nor dcron support that, and it's not mentioned in SUS.

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kc10
Predictor? Isn't it definitive?

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Flimm
This broke the back button.

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yellowsir
@reboot is not valid :(

~~~
low_key
Also, anything with "/0" gives a divide by zero exception:

for example:

    
    
      */0 * * * *

~~~
brianwawok
What does that even mean? Never used that one...

