A Weird Imagination

Identifying joystick devices

Posted in

Too many input devices#

On a modern computer there are often many input devices,

$ ls /dev/input/event* | wc -l
28

They are just identified by numbers, so it can be difficult to choose the right one and trial-and-error can get tiresome with so many. There is some help from the by-id and by-path listings:

$ ls -go --time-style=+ /dev/input/by-id/
...
lrwxrwxrwx 1 10  usb-045e_0291-if06-event-joystick -> ../event26
lrwxrwxrwx 1  6  usb-045e_0291-if06-joystick -> ../js6
lrwxrwxrwx 1 10  usb-0b43_0003-event-if00 -> ../event20
lrwxrwxrwx 1 10  usb-0b43_0003-event-joystick -> ../event19
lrwxrwxrwx 1  6  usb-0b43_0003-joystick -> ../js1
lrwxrwxrwx 1  9  usb-BTC_USB_Multimedia_Keyboard-event-if01 -> ../event2
lrwxrwxrwx 1  9  usb-BTC_USB_Multimedia_Keyboard-event-kbd -> ../event1
...

$ ls -go --time-style=+ /dev/input/by-path/
...
lrwxrwxrwx 1  9  pci-0000:00:1a.2-usb-0:2:1.0-event-kbd -> ../event1
lrwxrwxrwx 1  9  pci-0000:00:1a.2-usb-0:2:1.1-event -> ../event2
...
lrwxrwxrwx 1 10  pci-0000:00:1d.0-usb-0:1:1.6-event-joystick -> ../event26
lrwxrwxrwx 1  6  pci-0000:00:1d.0-usb-0:1:1.6-joystick -> ../js6
lrwxrwxrwx 1 10  pci-0000:00:1d.0-usb-0:2:1.0-event -> ../event20
lrwxrwxrwx 1 10  pci-0000:00:1d.0-usb-0:2:1.0-event-joystick -> ../event19
...

But, for the most part, those names aren't very helpful, especially since many joystick devices support 2 or 4 joysticks connected to the same device.

identify_evdev.py#

Enter identify_evdev.py:

$ identify_evdev.py
/dev/input/event22

Where /dev/input/event22 is the device of the joystick I touched after running identify_evdev.py.

Read more…

Listing files into a file

Posted in

The problem#

$ ls > file

doesn't do what you expect:

$ touch foo
$ touch bar
$ ls > filelist
$ cat filelist
bar
filelist
foo

You probably didn't expect, or want, filelist to be listed in filelist.

The solution#

$ filelist=$(ls); echo "$filelist" >filelist

Read more…