/usr/share/doc/mpg321/README.Debian is in mpg321 0.3.2-1.1ubuntu1.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 | The mpg321 package installs an alternative to mpg123 when it's installing.
This means that mpg321 will actually be called if you run mpg123,
even if you have mpg123 installed. If you want to override this default,
see update-alternatives(8) ('man update-alternatives').
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