> My biggest successes have been extracting these parts into very small stand-alone shell scripts which the Python application then invokes ... That's a clever

> My biggest successes have been extracting these parts into very small stand-alone shell scripts which the Python application then invokes ... That's a clever way to go. Sometimes the other way around works too: taking the most fiddly manipulations (say, date or time intervals) and re-homing them to a small Python script, but leaving the bash intact.