====== Renaming USB serial devices ======

When you connect an **usb-serial** adapter to a GNU/Linux host, it gets named something like **ttyUSB0**. Other similar devices get the name with subsequent numbers: **ttyUSB1**, **ttyUSB2**, etc. If you want a predictable device name, you can use **udev rules**.

In the following examples you can assign a predictable name by **USB slot position** or by **vendor/product** of the USB adapter.

Once the device is connected, inspect the udev subsystem about it;

<code>
udevadm info -a -p  $(udevadm info -q path -n /dev/ttyUSB0)
</code>

You can choose among many attributes to identify the device.

The following example will identify the device by the USB position, which is also reported by **dmesg**:

<code>
usb 1-2.3: pl2303 converter now attached to ttyUSB0
</code>

Create a file **/etc/udev/rules.d/10-local.rules** with the following line:

<file>
ACTION=="add", SUBSYSTEMS=="usb", KERNELS=="1-2.3", SYMLINK+="usbserial_A"
</file>

Otherwise you can select by vendor/product, with another line like this one:

<file>
ACTION=="add", ATTRS{idVendor}=="067b", ATTRS{idProduct}=="2303", SYMLINK+="usbserial_B"
</file>

Let the udev subsystem to re-read the rules:

<code>
udevadm trigger
</code>

Now, when you plug the USB adapter, a symlink will be created **%%/dev/usbserial_A -> ttyUSB0%%**.

If more than one rule match, more than one symlink will be created.