Linux 和 bash - 如何获取输入设备事件的设备名称？

Question

I'm trying to automate the process of getting a game controller's device event and checking its name, then if the name matches a string, pass the event to another program.

By hand, I run evtest /dev/input/eventXX to check the name of the input device, then keyboard interrupt(ctrl-c) to stop it. If that device matches the name of a certain type of game controller, I run the command xboxdrv --evtest /dev/input/eventXX with the same event number.

However, because the "evtest" command continues to print the input device's outputs instead of terminating after printing the name and only exits on keyboard interrupt, I'm not sure how I could have the bash script get the name of the device.

I'm still learning bash so there may be syntax errors in my code. But, here it is:

#!/bin/sh
WiiUGCName="Wii U Gamecube Adapter Port"

#find the controller(s)
NumberOfEvents=$(ls /dev/input | grep -c event*)

echo "Number of input devices: $NumberOfEvents"

#launch xboxdrv for each controller
i=0
while [ $i < $NumberOfEvents ]; do
    echo "loop"
    OccurrencesOfName=$(evtest /dev/input/event$i | grep -c "$WiiUGCName")
    echo "Occurrences: $OccurrencesOfName"
    if [ $OccurrencesOfName>0 ]; then
        echo "Controller found"
        #launch xboxdrv here
    else
        echo "no controller found"
    fi
    let i=i+1
done

All this code actually does right now is hang at that evtest since it cannot be terminated.

Answer 1

The simplest option is to give evtest some reasonable time to print the interesting portion of the output, say 1 second, and then kill it. If you place that code in a shell function, the resulting code can remain readable. For example, replace:

OccurrencesOfName=$(evtest /dev/input/event$i | grep -c "$WiiUGCName")

with the invocation of a shell function:

OccurrencesOfName=$(evtest_and_exit | grep -c "$WiiUGCName")

evtest_and_exit can be defined as follows:

evtest_and_exit() {
    local evtest_pid
    evtest /dev/input/event$i &
    evtest_pid=$!
    sleep 1  # give evtest time to produce output
    kill $evtest_pid
}