If the system uses UDEV, all permissions are set by UDEV, we cannot set them the way we used to.
When using UDEV, you can modify the permissions by modifying the RealPort UDEV script, called “10-dgrp.rules”
in the udev directory in /etc/udev*
By default we have this in there:
KERNEL=“tty_dgrp*”, PROGRAM=“/usr/bin/dgrp_udev %k”, NAME=“%c”
KERNEL=“cu_dgrp*”, PROGRAM=“/usr/bin/dgrp_udev %k”, NAME=“%c”
KERNEL=“pr_dgrp*”, PROGRAM=“/usr/bin/dgrp_udev %k”, NAME=“%c”
(Section: Controlling permissions and ownership)
Controlling permissions and ownership
udev allows you to use additional assignments in rules to control ownership and permission attributes on each device.
The GROUP assignment allows you to define which Unix group should own the device node. Here is an example rule which defines that the video group will own the framebuffer devices:
KERNEL==“fb[0-9]*”, NAME=“fb/%n”, SYMLINK+=“%k”, GROUP="video"The OWNER key, perhaps less useful, allows you to define which Unix user should have ownership permissions on the device node. Assuming the slightly odd situation where you would want john to own your floppy devices, you could use:
KERNEL==“fd[0-9]*”, OWNER="john"udev defaults to creating nodes with Unix permissions of 0660 (read/write to owner and group). If you need to, you can override these defaults on certain devices using rules including the MODE assignment. As an example, the following rule defines that the inotify node shall be readable and writable to everyone:
KERNEL==“inotify”, NAME=“misc/%k”, SYMLINK+=“%k”, MODE=“0666”
It should also be noted that with UDEV, “/dev” is now a tmpfs “temp file system”. This means the settings do not stay after a system reboot.