Question

what does this crontab syntax mean

"*/15 * * * 2-5"

I thought it means it runs every 15 mins past every hour, from Tuesday to Saturday.
can I change that to:

"*/55 * * * 2-5"

that didn’t seem to work for some reason.

Can you explain what is the */ at the beginning ?

Thanks

Answer 1

Your first example should be ok if you want it to run every 15 minutes. 2-5 on the 5th position is referring to Tuesday to Friday.

What do you want to accomplish with */55?

A good syntax explanation can be found in Wikipedia:

Asterisk ( * )

The asterisk indicates that the cron
expression will match for all values
of the field; e.g., using an asterisk
in the 4th field (month) would
indicate every month.

Slash ( / )

Slashes are used to describe
increments of ranges. For example
3-59/15 in the 1st field (minutes)
would indicate the 3rd minute of the
hour and every 15 minutes thereafter.
The form “*/…” is equivalent to the
form “0-59/…”.