UTF-8

To determine the file type of the file "sample.txt" you just type:
file sample.txt
Usually it'll tell you only that it is a text file. To get to know more about the encoding type:
enca -L none sample.text
The -L switch tells the program what language is used in the file. If you don't know, just use none.
To convert the encoding from ISO-8859-1 (latin1) to UTF-8:
iconv --from-code=ISO-8859-1 --to-code=UTF-8 sample_iso8859-1.txt > sample_utf-8.txt