Cronjob is triggered automatically - linux

I have created a cron job, which needs to be triggered at 00:01 on the daily basis. Below are the details:
Cronjob configuration:
01 00 * * * root /usr/bin/python /opt/scripts/tune.py -t & >/dev/null &
Permissions and location of file:
root#localhost:/etc/cron.d# ll /etc/cron.d/database_tuning
-rw-r--r-- 1 root root 80 Oct 12 01:04 /etc/cron.d/database_tuning
However, this cronjob is not triggered automatically at the specified interval. Now, once I edit this file, and change time to 01:12 AM like (12 01 * * *). then it is triggered automatically successfully. So I confirmed that there is no problem with the script/environment, but I am not able to understand that why cronjob is not triggered at 00:01 AM. What is the best possible to debug this ?

As Ali also stated, the hour field must be a value between 0-23, so it won't work if you write 00.
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 Sunday, or use names)
A field may contain an asterisk (*), which always stands for
"first-last".
Take a look at crontab manual page.

Related

run cron job between 00:00 - 00:02 - 04:00 - 23:59 on every hour

I want to run a cron job between 0:00am - 02:00am - 04:00am and 23:59am on every hour.
I want to know if this is the correct syntax.
0,0-59 0-2,4-23/1 * * *
Thanks!
No, your syntax is not correctly formatted.
You can use:
0 0 0/1,0-2 ? * *
This will run according to the following rules:
At second :00, at minute :00, every hour between 00am and 02am,
and every hour starting at 00am, of every day
You can check CRON syntax with an explanation at:Cron Expression Generator & Explainer.
Also, I think this site has a really good breakdown to help understand what each section of the CRON expression relates to.
Edit: I just noticed you had the second part about running at 23:59. For this you will need to set up a second CRON job:
0 59 23 * * ? *
Use Case: At 23:59:00pm every day

WebJob Crontab schedule running at the top of the hour and every 15 min thereafter

I'm trying to come up with a schedule for my Azure WebJob in crontab format that will run every 15 minutes but exactly at h:00, h:15, h:30 and h:45.
The one that I'm using for my web job right now is:
{ "schedule": "0 0/15 * * * *" }
But this doesn't make it run exactly at the top of the hour then every 15 minutes thereafter.
I want the job to keep running -- no end date/time. However, when I launch the webjob, it should not start running until it's h:00, h:15, h:30 or h:45 -- whichever happens to be next. For example, if I deploy my webJob at 8:37 AM, the first run should be at 8:45 AM AND it should then keep running every 15 minutes after that.
I'd appreciate some help with this. Thanks.
Use */15 for minutes:
0 */15 * * * *
From this answer
field allowed values
----- --------------
second 0-59
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)
So for you :
{ "schedule": "0 0,15,30,45 * * * *" }

I need help using cronjob

I'm trying to write a cron job to run automatically a PHP file after 30 days. The PHP file has write permission 777.
Here is my code:
* * * */30 * php -f /var/www/virtual/my_domain_name.com/htdocs/./file.php > /dev/null 2>&1
But this is not working, I got no errors.
When i try:
* * * * * php -f /var/www/virtual/my_domain_name.com/htdocs/./file.php > /dev/null 2>&1
The script works, then it executes the file every second from.
Any ideas?
Putting */30 in the 4th field would cause the job to run only in the 30th month of the year, and every 30 months thereafter during the year -- i.e., never.
Putting */30 in the 3rd field (day of month) would cause it to run on the 30th day of each month (and on the 60th, 90th, ... day of the month if there were such a thing). And given the *s in the other fields, it would run once a minute on that day -- and never in February. I doubt that that's what you want.
If you want a job to run once a month, that's easy:
0 0 12 * * php ...
This will run the job at midnight on the 12th day of each month. Adjust the first two fields to pick a different time and the third to pick a different day.
There is no syntax for running a job once every 30 days. If that's really what you want, you can schedule the job to run once every day:
0 0 * * * php ...
and then have the job itself determine whether the current day is a multiple of 30.

18 06,12,18 * * * what does this mean in cron issue time?

WHat does the following line mean in Linux - Chrone Time Scheduling
18 06,12,18 * *
Is it it will run 6.18 am, 12.18 pm and 6.18 pm every day for all month of all week.?
Check it out in manual page for crontab, either online or by typing man 5 crontab in terminal.
It means that the command will run at 6:18, 12:18 and 18:18 every day.
Also, I think you're missing one asterix (*) - there should be five time and date fields, and you've got only four (although, in post title, you've got five). Anyway, the full definition would look like:
18 06,12,18 * * *
You can test your cron job on cron job generator site page.
This is very helpful.
Just select whatever options you want for cron job and generate the code.

Cron expression for one day occurs every hour

I need cron expression which allows to me run scheduler by the following rules:
Starts 12:00 am on Friday (pacific time)
ends 12:00 am on Saturday (pacific time)
And between these two dates it must occurs every hour
i can write something like "0 0 12/1 ? * FRI-SAT" but ofcourse it is not correct.
How to set simple range from 12-00 FRI to 12-00 SAT?
Try this expression
0 0 12-23,00-12 ? * FRI,SAT
and you can verify the next scheduled time here at http://www.cronmaker.com/ by entering this expression.
I'm guessing that you will probably need to set up two triggers, one that starts at 12:00 pm Friday and ends at midnight and triggers every hour and one for Saturday starting at 00:00 am and ends at 12:00 pm. So something like this
0 0 12-23 ? * FRI
0 0 0-12 ? * SAT
Cron Trigger Tutorial
Edit
Also have a look at Cron Maker as it will generate the cron expression for you. and also show when it will trigger.
If a cron expression is not easily discernible you can always build your own trigger.
I'm thinking something like this may help:
var jobDetail;
var days = new DayOfWeek[] {DayOfWeek.Friday, DayOfWeek.Saturday};
var trigger = TriggerBuilder.Create()
.ForJob(jobDetail)
.WithDailyTimeIntervalSchedule(x => x.WithIntervalInHours(1)
.OnDaysOfTheWeek(days)
.StartingDailyAt(TimeOfDay.HourAndMinuteOfDay(0, 0)));

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