Redirect to X11 :0

[davemha]

Hi all,
I'm trying to get the input from a USB barcode scanner to be entered into a webform.

I've tried the softwedge package, which works, but only supports 1D barcodes. I need to read in 2D barcodes; as soon as I try with softwedge, softwedge crashes.

I wrote a (very) little shell script to spit out the scan:

while true; do
    cat /dev/ttyUSB1
done

Works great for the shell or any process I run within that tty. What I really want to do is run my little script but have it put the scan into ANY process that is in focus (like the webform field in Firefox).

If I can't, my next thing would be to try to dig into softwedge and see if I can figure out how to make it work with 2D barcodes. Problem is, I'm not very good with C, and I know nothing about X programming.

This is on Ubuntu 14.04.

[schragge]

I guess some combination of a command-line X clipboard manipulation tool like xclip or xsel with an input automation tool like xdotool or xmacroplay may do the trick.

[davemha]

xdotool is an awesome find, thanks schragge. It's kind of slow but, using xdotool I was able to turn my script into a system-wide keypress event generator for my barcode scanner. Here's my new script, if anyone is interested.

read_ttyUSB1.sh:

#!/usr/bin/env bash
stty 57600 sane -echo -echok -icrnl -ixon -icanon -opost -onlcr time 3 min 0 < /dev/ttyUSB1
while true; do
    cat /dev/ttyUSB1 | sed -e 's/\(.\)/\1 /g' |\
               sed s/,/comma/g | \
               sed s/@/at/g |\
               while read LINE; do
        LINE=`echo $LINE Return`
        xdotool key $LINE 2>/dev/null
    done
done

Put that in the background with "read_ttyUSB1.sh &" and it just works!

xdotool doesn't parse all keys directly, hence the sed conversions for comma and at. I may run into other problems like that down the road but should be able to take care of them.

Also, my scanner doesn't have a speaker so I'm planning on adding a beep from the PC speaker.

[schragge]

You can put several sed commands into one sed call:

sed 's/./& /g; s/,/comma/g; s/@/at/g; s/$/Return/' /dev/ttyUSB1

[davemha]

Nice, didn't know that. Streamlining is good, I'll update it with that later. In the meantime, I added a beep feature. Turns out there isn't a PC speaker on this all-in-one kiosk I'm using, but there are Alsa speakers. So here's my solution for that (Thanks for the original idea go to Ryne Everett on StackExchange):

#!/usr/bin/env bash
_alarm() {
  ( \speaker-test --frequency $1 --test sine )&
  pid=$!
  \sleep 0.${2}s
  \kill -9 $pid
}


stty 57600 sane -echo -echok -icrnl -ixon -icanon -opost -onlcr time 3 min 0 < /dev/ttyUSB1
while true; do
    cat /dev/ttyUSB1 | sed -e 's/\(.\)/\1 /g' |\
               sed s/,/comma/g | \
               sed s/@/at/g |\
               while read LINE; do
        if [ "$LINE" != "" ]; then
            LINE=`echo $LINE Return`
            xdotool key $LINE 2> /dev/null
            if [ "`echo $LINE | grep '^at'`" != "" ]; then
                _alarm 1200 120 &> /dev/null
            fi
        fi
    done 2> /dev/null
done