
Crontab.guru – cron schedule expression editor - Amorymeltzer
https://crontab.guru/
======
FillardMillmore
I just so happened to use this page today and have used it many times in the
past. It's very useful for just double-checking my syntax. It's not like cron
has a complicated syntax but for some reason I can't ever seem to commit it to
memory, especially for the slightly trickier things like doing something every
15 minutes on the second Saturday of every month.

Part of my problem with committing the syntax to memory likely stems from the
fact that I've always had pages like this one to fall back on.

~~~
ben509
I can't recall it either; and at 5 fields it's a case study of the problem of
positional syntax. Even if we're a minority, we're a significant minority who
find we have to check the man page to either read or write, thus defeating the
savings from brevity.

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luckylion
Cronitor isn't the first and probably won't be the last, but what is it with
these stealth companies? _Crafted in Berkeley_ is the only info that somewhat
narrows down who is behind it ("somebody that was in Berkeley when this was
built"), but nothing else does. Even "contact us" just gives you an Email.
There's a phone number for support, but no company, nothing.

Who trusts sensitive information like cron output to anonymous third parties?
Is "but they are charging me, so I know I can trust them" the trigger here?

~~~
encoderer
Hi luckylion,

My name is Shane, and my co-founder is August. We did an indie hackers
interview about Cronitor a few years ago and we’ve been pretty active here on
HN.

I’m happy to answer any questions you have.

~~~
luckylion
I guess the only question is: why are you not actively communicating who is
behind the tool? The impression it gives me is that either you don't want your
names attached to the project, or that you fear that attaching your names to
the project would hurt prospects.

Or is it just an oversight and you didn't intend to run the service
anonymously?

~~~
encoderer
On day one when we launched Cronitor (in 2014) I was a Sr Engineer at a tech
company and August was the 1st Engineer at a YC-funded startup. Neither of us
wanted to trade on that for our side project.

Over the years, as Cronitor grew into a successful business, we've shared a
lot about it publicly with our names attached but I never felt a calling to
put our faces on a webpage. I have always been more eager to collect customer
testimonials and share what they have to say about us. Maybe I'm just shy.

~~~
luckylion
It's not even about putting your face onto it, that's understandable. It's
just that there's nothing. Sure, you can dig around, find the termly-page and
then at the end find some info, but that looks so scammy to me, while the rest
of the page doesn't give me that vibe at all.

Typically, I associate "we don't tell you who we are" with grey/black stuff. A
DDOS service would only provide an email address for obvious reasons. But for
a company? If somebody wants to sue you, they will find out who you are in any
case. I wouldn't expect pictures, CVs etc, but a contact page that doesn't
list a company/individual name and a street address triggers two feelings: a)
scam or b) run from a bedroom. Neither makes me want to trust you with
critical infrastructure (and here's where I'm irrational: _seeing_ a company
name and address is enough, unless there's some suspicion, I won't even dig
into it to see whether the company or address actually exists).

As I mentioned, it's not specific to you at all, a lot of SaaS companies do
this, and I don't understand it. Might be a cultural thing. In Germany, you're
breaking the law if you're running a commercial site and are not clearly
stating who you are, so maybe that's why alarms are ringing in my head when I
don't see it.

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ganeshkrishnan
Note that for Java/Spring cron there is an extra field for "Seconds" so it has
one extra field to be configured.

~~~
psilocipher
Java Spring documentation also claims to support the question mark vs.
asterisk character, however it seems that some versions treat them
identically, where the ? is supposed to be a random value and the asterisk is
supposed to mean every value...

[https://stackoverflow.com/questions/30341067/difference-
betw...](https://stackoverflow.com/questions/30341067/difference-between-and-
in-spring-scheduledcron)

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betaby
Better use systemd as a reliable cron replacement
[https://wiki.archlinux.org/index.php/Systemd/Timers](https://wiki.archlinux.org/index.php/Systemd/Timers)

~~~
fractalf
And exacly why is that better than cron?

~~~
trulyrandom
Because it integrates nicely with the rest of systemd. If you use systemd,
there's no real reason to also have a crond running.

~~~
FillardMillmore
I think both have their use cases. For quick and dirty things (like manual
logging/system performance), cron works just fine and is quicker to set up.
For tasks that require dependencies or have to happen at very specific points
in time (like immediately after the network services are started), systemd is
more suited to the task.

There are of course quite a few people who dislike systemd for justifiable
reasons (but I doubt it receives the disdain that SELinux does), here's a
starting point:

[https://ihatesystemd.com/](https://ihatesystemd.com/)

That said, I very much like systemd and I hope it isn't going anywhere. I
think it's improved on a lot of things from the SysVinit days and I hope and
believe that its shortcomings will be addressed and improved in the future.

~~~
theamk
My problem with cron for short tasks is that pretty often I forget to add
logging and/or locking. And then machine runs out of resources because of all
the parallel jobs, and there aren’t even any logs.

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brian_herman__
This website is great! I use it all the time at work to help me grok the
crontab expressions.

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Karunamon
I've got this website on a permanent spot in my bookmarks bar. It's kinda like
tar - I use it enough that I should have absorbed the syntax by repetition and
osmosis, but I still find myself looking up the syntax for cron "just to be
sure" and running tar with --help.

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watersb
Perhaps off-topic, but this reminded me of Lingon, a macOS app for editing
launchd services.

[https://www.peterborgapps.com/lingon/](https://www.peterborgapps.com/lingon/)

~~~
frou_dh
I settled on LaunchControl instead because I was impressed by the semantic
understanding of fields that it has. If a job goes wrong it frequently has a
1-click suggestion to fix it or to facilitate debugging.

[https://www.soma-zone.com/LaunchControl/](https://www.soma-
zone.com/LaunchControl/)

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eqmvii
Love this tool. Use it every time I write or review crontab code.

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y4mi
> _We created Cronitor because cron itself can 't alert you if your jobs fail
> or never start._

That's a lie. A mail is sent on failed jobs. The receiving mailbox is by
default the executing user (so usually root) There is also an entry into the
systemlog which should already be monitored.

The user might not get the notifications because he doesn't pay attention, but
cron does notify.

~~~
ggm
_That 's a lie. A mail is sent on failed jobs._

Please don't use the lie word: it goes to intentionality. It's wrong, true:
Cron has (for a very long time) been designed to mail and log on failure.

The thing is that a huge number of deployments these days don't run functional
mail send, and so the failure states go to /dev/null (in effect)

Also, cron can fail to run: Linux moved cron to a different execution state
from BSD, which has also introduced (on linux) the interaction between cron
and anacron. Changing the state of cron.d/ doesn't always register in cron,
and cron won't always send mail if it doesn't know new things have to be run.
The older crontab -e method reliably made cron re-read the state of the file.

(I think this predated Vixie cron, cron existed since time immemorial in
UNIXEN. Vix improved things, but the underlying system behaviour was
established before he coded in this space)

~~~
scbrg
> Please don't use the lie word: it goes to intentionality.

If someone built a whole product around it - and use it as their marketing
pitch when it takes like 30 seconds of man-page reading to find out that it's
wrong, I'd argue you have some fairly good reason to assume intentionality.

(That said, yes, I agree that there are failure states in traditional cron
that won't alert you with an email, so the service might of course be useful.)

