Here's what I did, and it seems to work in this situation. At least, it shows me an error, whereas running from the command line as the user doesn't show the error.
Step 1: I put this line temporarily in the user's crontab:
* * * * * /usr/bin/env > /home/username/tmp/cron-env
then took it out once the file was written.
Step 2: Made myself a little run-as-cron bash script containing:
#!/bin/bash
/usr/bin/env -i $(cat /home/username/tmp/cron-env) "$@"
So then, as the user in question, I was able to
run-as-cron /the/problematic/script --with arguments --and parameters
This solution could obviously be expanded to make use of sudo or such for more flexibility.
Hope this helps others.
The following will run script on the 1st of Jan, Apr, Jul and Oct at 03:30
30 03 01 Jan,Apr,Jul,Oct * /path/to/script
Alternatively, but less obvious
30 03 01 */3 * /path/to/script
Will run every three months at 03:30 on the 1st of Jan,Apr,Jul and Oct.
Best Answer
You are looking for something like this (via crontab -e):
15 is the hour and 0 is the minute that the script is run. Day of month, month, and day of week get wildcards so that the script gets run daily.