# Cron expression: difference between 0/1, 1/1 and *

In a cron expression, what is the difference between `0/1`, `1/1` and `*` ?

• The `/` is stepping, explained really well here: publib.boulder.ibm.com/infocenter/db2luw/v9r5/index.jsp?topic=/… – NickW Mar 19 '14 at 12:36
• Why the down vote, please? Any missing information? Does the question belong to another stackexchange site? – sdabet Mar 19 '14 at 12:47
• Mouse over the down arrow; the popup says "This question does not show any research effort; it is unclear or not useful". Downvotes without comment may be presumed to be for at least one of those reasons - though I note the downvoter has since retracted. – MadHatter supports Monica Mar 19 '14 at 14:33
• Thanks @MadHatter, I just don't have enough reputation yet to see the vote details – sdabet Mar 19 '14 at 15:55

It depends on where the terms are located

• `0/1` means starting at 0 every 1.
• `1/1` means starting at 1 every 1.
• `*` means all possible values.

so

• For the minutes, hours, and day of week columns the `0/1` and `*` are equivalent as these are 0 based.

• For the Day Of Month and Month columns `1/1` and `*` are equivalent as these are 1 based.

• Does it make any sense to use `0/1` for months then? What would happen? – sdabet Apr 25 '15 at 5:26

In crontab definition, the meaning of the five date/time fields are :

1. At which minutes of the hour (so from 0 to 59)
2. At which hour of the day (so from 0 to 23)
3. At which day of the month (so from 1 to 31)
4. At which month of the year (so from 1 to 12 or names - Jan, Feb, ...)
5. At which day of the week (so from 0 to 6 or names - Sun, Mon, ...)

A * means from the first to the last element of the range. A n/x means starting at n, at every x values.

In your case, this can be translated by :

1. At minutes 0
2. Starting at midnight, every hour (which is similar to *)
3. Each day of the month
4. Starting the first month (January), every month (which is similar to *)
5. Each day of the week (for the first *)

The end looks incorrect (? *) as it is in the place of the command. Or in the place of the username & command if taken from a file under `/etc/cron.d/` and not from the crontab of a specific user.

The 0/1 means every 1 min or every mintue and 1/1 means evey month i think,but i m not sure it will work that way for month.

• Then what is the difference between `0/1`, `1/1` and `*` ? – sdabet Mar 19 '14 at 12:38
• The 0/1 is in the hour position. – user9517 supports GoFundMonica Mar 19 '14 at 12:42
• that one is for hour – vic Mar 19 '14 at 12:42
• Sure, but can I replace the hour part `0/1` by `1/1` for instance ? Will it mean the same? – sdabet Mar 19 '14 at 12:45
• Isn't the same as putting `0` or `1` then ? – sdabet Mar 19 '14 at 12:52