Need Help with Cron

[chobo2]

Hi

I am doing some exercsises in my book but I don't know if I did them right since I don't know how to test them can someone check them over?

Write the lines that you coulde use in your crontab to schedule the /bin/sample command to run:

1.Every Friday at 1:30am

30 01 * * 6 /bin/sample

2. At 4:30pm on May 15th only

30 16 15 5 */bin/sample
3. at 4:00pm and 4:30pm on the first Sunday of every month
0,30 16 * 0 /bin/sample


4. every 10mins from 9:00am to 5:00pm on Monday
*/10 09-17 * * 1 /bin/sample
5. at 8:15 am and 6:30 pm Monday to friday.
15,30 08,18 * * 0-6 /bin/sample



Also I found this example from a site

If you wanted to run a command every day at a certain time for the first week of the month you would enter in 1-7 for the day field. An example of this type of entry would be:

15,30 */2 1-7 * * joey /usr/bin/somecommand >> /dev/null 2>&1

This would run somecommand every 2 hours at the 15's and 30's (2:15, 2:30, 4:15, 4:30 etc) for the first 7 days of the month.

but I don't see how this one works since I don't get how it only knows how to do it the first 1-7days of the month.


I choose suse section since I am using suse and was not sure if it changes depending on linux version.

If this is run please put it where it should be.

[ribbie]

When I learned cron jobs I just changed the time and date settings on the machine to the desired test times to see if the job was running properly.

I also used webmin to schedule them, if you're allowed to use webmin I would suggest it because those questions can be answered in a couple of clicks.

[Lazydog]

Because the field that the '1-7' is in is the day field and the month field is every month '*'.

Each crontab command line is comprised of six positional fields specifying the time , date and shell script or command to be run. The format of the crontab command line is described as follows:

Field
Minute
Hour
Day of Month
Month
Day of Week
Command

Valid values
0-59
0-23
1-31
1-12
0-7
Command path/command

The day-of-week field accepts either 0 or 7 as a value for Sunday. Any of the time/date fields can also contain an asterisk (*) indicating the entire range of values. Additionally, month and day-of-week fields can contain name (first 3 letters of month or day) values as indicated below.

Field
Valid Entries (case insensitive)

Days of the week
sun, mon, tue, wed, thu, fri, sat

SUN, MON, TUE, WED, THU, FRI, SAT

Months of year
jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec

JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC

When numbers are used, you can specify a range of values separated by a hyphen or a list of values separated by commas. In other words specifying 2-5 in the hour field means 2AM, 3AM, 4AM and 5AM, while specifying 2,5 means only 2AM and 5AM.