Support writing to IO streams other than stdout & std err

[neimanpinchas]

General

No way to write into node process stdio streams other then stdout & stderr,
needing something like process.stdio[4].write(buffer)

In child proccess there is cp.stdio, but having no way to intercept it in the child

[addaleax]

The fs and net APIs supports working with raw file descriptors; e.g.:

var readableFd4 = fs.createReadStream('', {fd: 4});
var writableFd4 = fs.createWriteStream('', {fd: 4});

// This will give you a duplex, but it will only work if fd 4 refers to a pipe or socket.
var duplexSocketFd4 = new net.Socket({fd: 4});

Does that help?

[neimanpinchas]

Thanks for the clear response I think i got it, please confirm if the following is correct. //in parent .js var cp=require("child_process").spawn var child=cp("child.js") child.stdout.on("data",(data)=>{ console.log("child reported launched") }) child.stdio[4].on("data",(data)=>{ console.log("child acting nice") }) //in child.js console.log("launched") var writableFd4 = fs.createWriteStream('', {fd: 4}); writableFd4.write("thanks for launching me") While i was waiting for an answer, i looked around in the node github repository and i found in /lib <https://github.com/nodejs/node/tree/master/lib>/internal <https://github.com/nodejs/node/tree/master/lib/internal>/process <https://github.com/nodejs/node/tree/master/lib/internal/process>/stdio.js using this function createWritableStdioStream() i am wondering where it is declared and how it could be called from a node script Appreciating your help

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On Thu, Jun 15, 2017 at 3:39 PM, Anna Henningsen ***@***.***> wrote: The fs and net APIs supports working with raw file descriptors; e.g.: var readableFd4 = fs.createReadStream('', {fd: 4});var writableFd4 = fs.createWriteStream('', {fd: 4}); // This will give you a duplex, but it will only work if fd 4 refers to a pipe or socket.var duplexSocketFd4 = new net.Socket({fd: 4}); Does that help? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#673 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AQJ0rR1BtUz2NmQa5MBSSc3K87SFmhsTks5sEYhdgaJpZM4N7pcN> .

-- Pinchas S. Neiman 845.213.1229 #2

[addaleax]

I think your code is basically right, yes; but you might need to call spawn with {stdio: ['inherit', 'inherit', 'inherit', 'ipc', 'pipe']} or something like that to make sure enough stdio pipes are created.

using this function createWritableStdioStream() i am wondering where it is declared and how it could be called from a node script

It’s not available to scripts, and I personally strongly dislike that the Node API forces you to use fs.create[Write,Read]Stream or net.Socket directly.

[neimanpinchas]

Thank you very much!

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On Thu, Jun 15, 2017 at 5:27 PM, Anna Henningsen ***@***.***> wrote: I think your code is basically right, yes; but you might need to call spawn with {stdio: ['inherit', 'inherit', 'inherit', 'ipc', 'pipe']} or something like that to make sure enough stdio pipes are created. using this function createWritableStdioStream() i am wondering where it is declared and how it could be called from a node script It’s not available to scripts, and I personally strongly dislike that the Node API forces you to use fs.create[Write,Read]Stream or net.Socket directly. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#673 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AQJ0rTu5OYf4chKYqQOwp7AvBH1og5hxks5sEaHIgaJpZM4N7pcN> .

-- Pinchas S. Neiman 845.213.1229 #2

[gireeshpunathil]

closing as answered.