fivemack | (Reply)

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On the other hand, if I start writing code this dense in unclear bashisms, my colleagues at work will disembowel me with spoons.

I think that if your code is preceded by a comment which says 'for each filename of format m12331246123468911531238951802368109467.mlog, print "C038.123312" where the number before the dot is the length of the original digit string and the number after is its first six digits', then it's reasonably clear; if it doesn't then it's pretty unclear whichever variant you use. (In particular with a comment it's immediately clear to the reader whether they actually need to check the implementation against the intention in order to achieve whatever goal they had in mind when they started reading the file, and there's a record of what your intention actually was!)