Message between bash and JavaScript via named pipes

Question

I have a JavaScript application that needs to start a Linux application.

Since I did not find any way to start the application and get when it ends, I made a bash script which launches the application, and sends a message via a named pipe when the app closes.

Until here, all's good, but I can't find a way to catch this message in the JavaScript.

Did someone know how to get the message in the JavaScript?

I did search, but I only found how to do this in C# and C++.

Sample from the JavaScript:

var test = spawn('sh', ['home/pi/play.sh', data.video_id]);

Just spawn a bash command which starts the script with the name of the video

Sample from the bash:

mkfifo btjpipe
if pgrep omxplayer
then
    echo "AR">btjpipe
else
    clear
    omxplayer $1 > dev/null
    echo "VE">btjpipe

Created the pipe, seeking if the player is already running, then either send AR ("Already Running") or start the player and send VE ("Video End").

What JavaScript engine and environment are you using? NodeJS? SilkJS? — T.J. Crowder
– T.J. Crowder, Commented Jul 24, 2013 at 7:45
I m on a raspeberry pi using raspbian (debian for raspberry pi), on chromium, with node.js — DrakaSAN
– DrakaSAN, Commented Jul 24, 2013 at 7:55
I've added the nodejs tag (really quite an important one for your question). No idea what you mean by "on chromium" -- if you're using Raspbian, you're not using Chrome OS, and the only other relevant Chromium I can think of is a web browser, but you're not doing this in a web browser. — T.J. Crowder
– T.J. Crowder, Commented Jul 24, 2013 at 7:56
I ve seen that, I was editing with some second late, forgot to add it — DrakaSAN
– DrakaSAN, Commented Jul 24, 2013 at 7:57

ElLocoCocoLoco · Accepted Answer · 2013-07-24 08:45:03Z

2

use child_process module and child.stdout to pipe the output where you want

var spawn = require('child_process').spawn;
var test = spawn('sh', ['home/pi/play.sh', data.video_id]);


test.stdin.pipe(process.stdin);
test.stdout.pipe(process.stdout);
test.stderr.pipe(process.stderr);

on this case to the current process

Maybe you can also trying using "exec" instead of spawn, you will get the output in the callback function.

edited Jul 24, 2013 at 8:45

answered Jul 24, 2013 at 8:35

ElLocoCocoLoco

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1 Comment

DrakaSAN Over a year ago

So with test.stdin.pipe(process.stdin);, if data where in the pipe, they ll now be in test?

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