TTY Attr

About

This is a small Node.js module based on a native C++ part for manipulating the terminal attributes via termios on file descriptor 0 (stdin). It allows to preserve and restore the terminal attributes and to set the terminal into raw mode.

Motivation

This NPM module is motivated by the problem that programs which are spawning TUI tools like tmux, lazygit or vim with the help of node-pty experience broken renderings of the TUI tools under Unix-like operating systems. The origin of this problem was already determined in 2020 and traced back to the usually necessary call to Node.js's setRawMode() uses the underlying libuv's UV_TTY_MODE_RAW which itself causes the problem. This TTY Attr module performs raw termios cfmakeraw() instead which does not cause this problem.

Installation

$ npm install tty-attr

Usage Example

import fs          from "node:fs"
import process     from "node:process"

import * as pty    from "node-pty"
import ttyAttr     from "tty-attr"

async function main (): Promise<void> {
    /*  get command and its arguments  */
    const cmd  = process.argv[2]
    const args = process.argv.slice(3).map(String)

    /*  spawn the command in a PTY  */
    const term = pty.spawn(cmd, args, {
        name:     process.env["TERM"] ?? "xterm-color",
        cols:     process.stdout.columns ?? 80,
        rows:     process.stdout.rows    ?? 24,
        cwd:      process.cwd(),
        env:      process.env as Record<string, string>,
        encoding: null
    })

    /*  pipe PTY output through to stdout  */
    term.onData((data: Buffer | string) => {
        const buf = Buffer.isBuffer(data) ? data : Buffer.from(data)
        for (let offset = 0; offset < buf.length; )
            offset += fs.writeSync(1, buf, offset, buf.length - offset)
    })

    /*  preserve terminal attributes and switch to raw mode  */
    if (process.stdin.isTTY) {
        ttyAttr.preserveAttr()
        ttyAttr.setRawMode()
    }

    /*  pipe stdin to the PTY input  */
    process.stdin.on("data", (data: Buffer) => {
        term.write(data)
    })
    process.stdin.resume()

    /*  handle terminal resize  */
    process.stdout.on("resize", () => {
        term.resize(
            process.stdout.columns ?? 80,
            process.stdout.rows    ?? 24
        )
    })

    /*  handle command exit  */
    term.onExit(({ exitCode }: { exitCode: number }) => {
        /*  restore terminal attributes  */
        if (process.stdin.isTTY)
            ttyAttr.restoreAttr()

        /*  pause stdin  */
        process.stdin.pause()

        /*  terminate gracefully  */
        process.exit(exitCode)
    })
}
main().catch((err: unknown) => {
    /*  print errors and terminate with error exit code  */
    process.stderr.write(`pass: ERROR: ${err instanceof Error ? err.message : String(err)}\n`)
    process.exit(1)
})

$ npx tsx example.ts ls -l
$ npx tsx example.ts vim
$ npx tsx example.ts tmux

License

Copyright © 2026 Dr. Ralf S. Engelschall (http://engelschall.com/)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.