Q:

Linux crontab what is the meaning of the line below?

i have a crontab line and i want to ask some expert what this line will do

10,40 * * * * sh /etc/test/script.sh

please tell me what will 10,40 do in this crontab -e file.i am new to crontab use

A:

*  *  *  *  *  command
-  -  -  -  -
|  |  |  |  |
|  |  |  |  +----- day of week (0 - 6) (Sunday = 0)
|  |  |  +------- month (1 - 12)
|  |  +--------- day (1 - 31)
|  +----------- hour (0 - 23)
+------------- min (0 - 59)

each position takes a comma-separated list of values.
this will execute sh /etc/test/script.sh at :10 and :40 every hour.
00:10, 00:40, 01:10, 01:40, ...
additionally
you can use / to specify an interval, i.e.
*/5 * * * * sh /etc/test/script.sh

to run it every 5 minutes.
wikipedia cron page

