I want to run a cron every 30 seconds between 00:00 and 11:55, every day, every month, any day of the month.
Is the following correct?
0/30 * 0-11 **
The format is as follows:
+---------------- minute (0 - 59)
| +------------- hour (0 - 23)
| | +---------- day of month (1 - 31)
| | | +------- month (1 - 12)
| | | | +---- day of week (0 - 6) (Sunday=0 or 7)
| | | | |
* * * * * command to be executed
So if you want to run every minute between 00.00 and 11.55, every day, every month, any day of the month, you need to combine two different lines:
* 0-10 * * * command
0-55 11 * * * command
Note that to run every 30 seconds you can use the trick described in Running a cron every 30 seconds.
You can try to run your script every 30 seconds using the following:
* 0-11 * * * (sleep 30; /path/to/executable)
So your crontab should looks like
* 0-11 * * * /path/to/executable
0-54 0-11 * * * (sleep 30; /path/to/executable)
Both command lines will be executed at the same time, but the second one will do a 30 seconds sleep before executing your command.
You can try to validate your cron statement with decoder
One of them you can find by the link: http://cronwtf.github.io/
Related
first are these cron anyway similar and if so which ones are redundant?
a) 15,35,55 * * * *
b) 15,35,55 */1 * * *
c) 15,35,55 0/1 * * *
What would be the cron to run at 35 and 15min/55min interchanged by an hour?
e.g
8am - 9am: 8:35am
9am - 10am: 9:15am and 9:55am
10am - 11am: 10:35am
11am - 12am: 11:15am and 11:55am
e.t.c
If you want to know what your cron is doing, then you can easily use crontab-guru to verify.
On your first question, yes the three examples are identical. The manual states the following :
man 5 crontab: Step values can be used in conjunction with ranges. Following a range with /<number> specifies skips of the
number's value through the range. For example, 0-23/2 can be used
in the 'hours' field to specify command execution for every other hour
(the alternative in the V7 standard is
0,2,4,6,8,10,12,14,16,18,20,22). Step values are also permitted
after an asterisk, so if specifying a job to be run every two hours,
you can use */2.
See the following examples:
# Example of job definition:
# .-------------------------- minute (0 - 59)
# | .----------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr ...
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7)
# | | | | |
# * * * * * command to be executed
15,35,55 * * * * command1
15,35,55 */1 * * * command2
15,35,55 0/1 * * * command3
15,35,55 0-23/1 * * * command4
So in the above example, command[1-4] will be executed at the same time, every hour on minute 15, 35 and 55
For your second question, it is best done this way :
# Example of job definition:
# .------------------------ minute (0 - 59)
# | .----------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr .
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7)
# | | | | |
# * * * * * command to be executed
15 0/2 * * * command1
35,55 1/2 * * * command1
15 8/2 * * * command2
35,55 9/2 * * * command2
15 8-18/2 * * * command3
35,55 9-18/2 * * * command3
Here, command1 will execute on {00,02,04,06,...,22}:15 and {01,03,05,...,23}:{35,15}, command2 will execute on {08,10,...,22}:15 and {09,11,...,23}:{35,15} and command3 will execute on {08,10,...,18}:15 and {09,11,...,17}:{35,15}.
I need to run task every day from 8-10 till 10-30 every 10 and 30 minute:
start at 8:10 ->
8:30 ->
9:10 ->
..
-> 10:30 finish
I have such cronjob:
10,30 8,9,10 * * *
will it be correct?
Yes, it is fine!
You can check it in http://crontab.guru/#10,30_8,9,10_*_*_*
Since you want to run it in an interval of hours, you can also say 8-10 to match hours from 8 to 10:
10,30 8-10 * * *
For your future reference, this is the format for cronjobs:
+---------------- minute (0 - 59)
| +------------- hour (0 - 23)
| | +---------- day of month (1 - 31)
| | | +------- month (1 - 12)
| | | | +---- day of week (0 - 6) (Sunday=0 or 7)
| | | | |
* * * * * command to be executed
A briefly shorter version would be
10,30 8-10 * * *
but yes, your version also works fine.
If you want to play around a bit, you can try crontab.guru.
I know I can set up cron for every minute, like
* * * * *
for once a day AFAIK it would be (lets say on 2am)
0 2 * * *
for every 30 minutes
0,30 * * * *
Now, is it possible to run cron job every minute, but during 30 minutes, once a day. For example I need the cron to run every day from 2am to 2:30, and during that time every minute.
thanks
Yes, sure. Use this:
0-30 2 * * *
^^^^ ^
| |
| on hour 2
on minutes from 0 to 30
Remember the format is as follows:
+---------------- minute (0 - 59)
| +------------- hour (0 - 23)
| | +---------- day of month (1 - 31)
| | | +------- month (1 - 12)
| | | | +---- day of week (0 - 6) (Sunday=0 or 7)
| | | | |
* * * * * command to be executed
I have an interesting problem with a cron job. I'm on a server with Cent OS and we're using Vixie cron. All this is very straighforward and i have a backup job that i want to run once every day at 01.00, so i created this simple crontab entry:
* 1 * * * /path/to/my/simpleJob.sh
What happens is this: at 01.00.02, the job runs as expected. Then cron (or something) continues to run the job every minute. Can anyone out there help me out? I have no idea what might be the root cause for this.
/M
The format is:
+---------------- minute (0 - 59)
| +------------- hour (0 - 23)
| | +---------- day of month (1 - 31)
| | | +------- month (1 - 12)
| | | | +---- day of week (0 - 6) (Sunday=0 or 7)
| | | | |
* * * * * command to be executed
So in your case being
* 1 * * * /path/to/my/simpleJob.sh
it means at hour 1, any minute.
To have it working just at 1.00, change it to:
0 1 * * * /path/to/my/simpleJob.sh
The CronSandbox at Dataphyx lets you play about with the date/time values - you see a schedule of runtimes for whatever combination you put in.
Is there any way to design the cron expression as to run every 70 minutes or 210 minutes i.e. > 60 minutes. I tried to search for this, but was not able to find this.
I finally went with a wrapper script that would do the required time checking which was called every 5 minutes(or the optimal recurring time).
How to accomplish such task in cron expression ?
Run every 70 minutes
* */1.1666
or
Run every 210 minutes
* */3.5
Basically, you need to run your cron every minute:
* * * * *
and let your script determine if its last execution dates from 70 or 210 minutes ago.
If it does, it would go on with the rest of the script.
If it does not, it would exit immediately.
In other words, don't try and put everything in the cron expression.
As commented by Keith Thompson, you could instead run that script less often (0 0/5 0 ? * * *), with a test at 70 minutes, or every 30 minutes (0 0/30 0 ? * * *) with a test at 210 minutes.
This answer is fairly identical to this and this
If you want to run a cron every n minutes, there are two cases to consider :
Every nth minute (60 is divisible by n)
Every nth minute starting from YYYY-MM-DD HH:MM:00 (generic)
The later covers the OP's case, but to remain generic I present both cases.
Every nth minute (60 is divisible by n)
This is valid for (n=1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30)
For this we use the combination of defining a range and a step value:
man 5 crontab: Step values can be used in conjunction
with ranges. Following a range with /<number> specifies
skips of the number's value through the range. For example,
0-23/2 can be used in the 'hours' field to specify command
execution for every other hour (the alternative in the V7
standard is 0,2,4,6,8,10,12,14,16,18,20,22). Step values are
also permitted after an asterisk, so if specifying a job to be
run every two hours, you can use */2.
See the following example:
# Example of job definition:
# .----------------- minute (0 - 59)
# | .------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr ...
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7)
# | | | | |
# * * * * * command to be executed
m/n * * * * command1
Here, command1 will be executed every nth minute from m till 59.
This means that :
if m<=n, they will always be spaced by n minutes.
Eg. m=2,n=10 :: the job will run on minutes 2,12,22,32,42,52
if m>n, they will always be spaced by n minutes, except at the
start of the hour.
Eg. m=12,n=10 :: the job will run on minutes
12,22,32,42,52. So here we have a jump of 20 minutes between
the 52nd and 12th minute.
note: you clearly see that if n does not divide 60
perfectly, you will have problems. Eg. m=0,n=11 runs on
0,11,22,33,44,55, so we only have 5 minutes to the next run.
Every nth minute starting from YYYY-MM-DDTHH:MM:00
If you want to run a cron every n minutes, you cannot do this cleanly with cron but it is possible. To do this you need to put a test in the cron where the test checks the time. This is best done when looking at the UNIX time stamp, the total seconds since 1970-01-01 00:00:00 UTC. Let's say we want to start from the moment McFly arrived in Riverdale:
% date -u -d '2015-10-21 07:28:00' +%s
1445412480
# Example of job definition:
# .---------------- minute (0 - 59)
# | .------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr ...
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7)
# | | | | |
# * * * * * command to be executed
* * * * * mintestcmd "2015-10-21 07:28:00" 7 && command1
*/10 * * * * mintestcmd "2015-10-21 07:00:00" 70 && command2
*/30 * * * * mintestcmd "2015-10-21 07:00:00" 210 && command3
with mintestcmd defined as
#!/usr/bin/env bash
starttime=$(date -d "$1" "+%s")
# return UTC time
now=$(date "+%s")
# get the amount of minutes
delta=$(( (now - starttime) / 60 ))
# set the modulo
modulo=$2
# do the test
(( delta >= 0 )) && (( delta % modulo == 0))
In the above examples we have:
command1 will run every 7 minutes on 2015-10-21 07:28:00, 2015-10-21 07:35:00, 2015-10-21 07:42:00, 2015-10-21 07:49:00, ...
command2 will run every 70 minutes from 2015-10-21 07:00:00 onwards. Since 70 is divisible by 10 and the start-time starts perfectly on the hour, we can set the cron to run every 10 minutes.
command3 will run every 210 minutes from 2015-10-21 07:00:00 onwards. Since 210 is divisible by 30 and the start-time starts perfectly on the hour, we can set the cron to run every 30 minutes.
Remark: UNIX time is given in UTC. If your cron runs in a
different time-zone which is influenced by daylight saving
time, it is advisable not to run the command between 2 and 3
o'clock. This could skip the command or run the command
twice (depending upon whether the time jumps forward or backwards)
Remark: UNIX time is not influenced by leap seconds
Remark: cron has no sub-second accuracy