duplicate writes to stdout on initial write

[logicminds]

Environment details

• OS: OS X
• OS version: 10.13
• node-pty version: 0.8.1

Issue description

I recently switched from the older pty module of which this project was forked from and noticed some differences in terms of how writing to stdout and stdin are handled.

Previously I was using processPty.stdin.write to write data to the console. The cli app (processPty) would read from stdin, process it and then write to stdout. Because the app wrote to stdout the processPty.on('data') event would be triggered.

After switching to node-pty I had to refactor the code and use processPty.write instead. I am hoping that this change runs the exact same code as processPty.stdin.write used to.

However, my observations shows that processPty.write might be sending to stdin and stdout. Additionally, my cli app then writes to stdout as well. So I get double outputs to stdout.

Furthermore, this seems to only occur on the first processPty.write as subsequent writes do not exhibit this double stdout write behavior. Almost as if the initial echo to stdout happens before my cli app has completed initialization/loading (takes about 1500 ms to initialize).

You can view this intended and actual behavior in my apps below:

• original working app
• refactored with node-pty app

This problem looks to be the same as #180 and #78

[Tyriar]

Can you share the old/new server code?

[Tyriar]

AFAIK node-pty is behaving correctly by duplicating here, this is what other terminals do as well:

I don't know why you're not seeing it with pty.js but I'm interested. term.stdin.write should be the same as term.write:

https://github.com/chjj/pty.js/blob/fe63a412574f45ee6bb6d8fab4a5c102107b5201/lib/pty.js#L331-L337

[Tyriar]

Maybe this is why? chjj/pty.js@ef6aa14