$ find . -exec file {} \;
$ iconv -f UTF-8 -t ISO-8859-15 in.txt > out.txt
$ iconv -t ISO-8859-15 in.txt > out.txt # ohne input-encoding
$ iconv --from-code UTF-8 --to-code ISO-8859-15 in.txt > out.txt
stackoverflow
Best way to convert text files between character sets?
How to convert ISO8859-15 to UTF8
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