perl -MDateTime -le '@wd=map {DateTime->new(locale=> "de", year=>1970,month=>1,day=>4+$_)->strftime("%a")} (0..6);print join",",@wd'

##</code><code>##

So.,Mo.,Di.,Mi.,Do.,Fr.,Sa.

##</code><code>##

So,Mo,Di,Mi,Do,Fr,Sa