Answer by chaos for Save only specific output to log file

When you call unison in your sync.sh script call it as follows:

unison ... 2>&1 | grep -vE '^[\|/-]|^$'

This will remove (-v) all line that match the regual expression: All line beginning with one of those characters: \|/-, or complete empty lines (^$).

Edit: If you want the cronjob to be filtered, use:

@reboot /path/to/sync.sh -batch 60 2>&1 | grep -vE '^[\|/-]|^$' >> /path/to/logfile