I'm trying to work out how to set up a custom udev rule to override permissions on serial ports (/dev/ttyS* and /dev/ttyUSB*) on CentOS 5.3 The default rule, in /etc/udev/rules.d/50-udev.rules has the line: KERNEL=="tty[A-Z]*", NAME="%k", GROUP="uucp", MODE="0660" and I would like the mode to be 0666 Various docs on web say that you shouldn't change 50-udev.rules, but instead create a new rule file that appears lexically before that rule - so I've created a file that contains the line: KERNEL=="tty[A-Z]*", NAME="%k", GROUP="uucp", MODE="0666" called 10-local.rules However, this doesn't work ... the /dev/ttyS* device files get the 'default' owner/group/perms (mode = '0600', uid = '0', gid = '0') If I rename the 10-local.rules to say 99-local.rules, then the device files get the owner/group/perms from 50-udev.rules (mode = '0660', uid = '0', gid = '14') I can get the mode set to 0666 by editing 50-udev.rules, however this seems wrong as you should be able to override the defaults without doing this. Anyone know if this is possible? Thanks James Pearson