How do I change the default owner, group, or permissions of my RAS/Xp devices in Linux?


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How do I change the default owner, group, or permissions of my RAS/Xp devices in Linux? How do I change the default owner, group, or permissions of my RAS/Xp devices in Linux?

This article will describe how to modify the default owner and permissions of your tty devices when using an Acceleport RAS or Xp product in a Linux environment.

The device nodes are created during system init when /etc/init.d/dgdm is run. On some versions of Linux, the path might be /etc/rc.d/init.d/dgdm. When this script creates the device nodes, it also sets what the default owner, group, and permissions for those nodes.

Here is an example from /etc/init.d/dgdm showing where he device node ownership, group, and permissions are set for the tty* device nodes:

TTY_OWN="root.0"
TTY_PERM="622"

There are other device types listed in the file such as DEBUG and CU, but it's the TTY device nodes that are created in /dev/, so these are what we want to modify. For example, to modify the device nodes so that uucp is the owner and group, you would make a change such as this:

TTY_OWN="uucp.uucp"

To then make these device nodes accessible to anyone on the system, you could do this:

TTY_PERM="666"

This might be something you'd want to do on an Acceleport RAS card for inbound/outbound modem use, such as with mgetty or other popular RAS or FAX applications.

Note: You may need to kill any processes running on those device nodes you want to change in order for the changes to take effect on the first reboot after the change. This is because a node needs to be removed in order to be recreated with the changes, and if a process is running on the device node, it won't be able to be removed.