It would be because cron runs as the root user.

Castget probably looks at the file path $HOME/.castgetrc. For your regular user, $HOME is probably /home/myamazingusername. For the root user, $HOME is probably /root .

You can get a root terminal session by running sudo -i in a terminal console window. You can try running castget there to see what happens.

Sudo -n:

-n, --non-interactive
  Avoid prompting the user for input of any kind.  If a
  password is required for the command to run, sudo, will
  display an error message and exit.

It’s just a nice thing to put in non-interactive scripts that use sudo. Sometimes you can end up with scripts that just wait endlessly for a password that will never be input because the script is being run non-interactively. The flag probably isn’t needed for a cron job, because root probably can sudo as any user without a password, but it doesn’t hurt either.

In line with the advice that running as root would likely not run with the correct file permissions (and would not read the correct config files), you probably want to run castget as your desktop user. Something like sudo -u mydesktopuser -n -- castget -c