Default Behaviour Python determines the encoding of stdout and stderr based on the value of the LC_CTYPE variable, but only if the stdout is a tty. So if I just output to the terminal, LC_CTYPE (or LC_ALL) define the encoding. However, when the output is piped to a file or to a different process, the encoding is not defined, and defaults to 7-bit ASCII. Example encoding.py: #!/usr/bin/env python2