If unprivileged users attempt to access a serial port, e.g. /dev/ttyS<n> or /dev/ttyUSB<n>, they will normally get an error message such as: Sorry, write access to UUCP lockfile directory denied. This message is actually due to permissions on the device, not the lockfile directory. If it is desired to allow specific unprivileged users to use ckermit to access serial ports, add those users to the "dialout" group. One way to accomplish this is using a command line such as: sudo usermod -a -G dialout <username> This will apply to future logins by that user. If you want to make the serial ports accessible to all users without adding them to the dialout group (not recommended), you can change the permissions of the serial device to 666, e.g., sudo chmod 666 /dev/ttyS<n>