[Nottingham] Sed regex problem

Andy White andy at milky.org.uk
Wed Oct 12 22:15:16 UTC 2011


> Can anyone help me out on this one, which has got me tearing out the
> small remaining amount of hair even after googling.  I want to match
> the minus sign character '-' in sed, but only if it occurs
> immediately after the 5th comma in a line that starts with '0'.  So
> far I can match a minus sign following a comma in a line starting
> with '0', but matching it only after the 5th comma is beyond me.

Something like 

sed -r '/^0(.*,.*)(,.*)(,.*)(,.*)(,\-).*/p'

> (More generally, I'm trying to simply invert the polarity of one of
> the fields of a .csv file.  Is there an easier approach than sed?)

do what?

I tend to use perl for pretty much everything, but I'm not certain
what you're trying to do.


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