I'm having trouble getting the following to work in my crontab: 30 1 * * * mailfilter -M ~/.mailfilterrc -L ~/autosave/log/mailfilter/mailfilter-`date +%Y%m%d%H%M`.log But the following appears to work: 30 1 * * * mailfilter -M ~/.mailfilterrc -L ~/autosave/log/mailfilter/mailfilter-`date -I`.log Which however doesn't give me the nice differentiating precision of `date +%Y%m%d%H%M`.