In my electron/reactjs app, i'm trying to open a terminal and launch somes commands.
My code looks like this :
const terminal = 'x-terminal-emulator';
const { spawn } = require('child_process');
spawn(terminal);
My terminal opens but i don't know how to launch commands in this terminal like 'cd /my/custom/path && ls'
Can someone help me please ? :)
Node.js child_process.spawn command have an option to specify the shell you want to use.
So I would use the opposite logic and launch directly the command within a particular shell (for exemple bash):
const { spawn } = require('child_process');
const terminal = '/bin/bash';
let cmd = 'echo $SHELL';
spawn(cmd, { shell: terminal })
.stdout.on('data', (data) => {
console.log(`stdout: ${data}`); //-> stdout: /bin/bash
});
Related
If I have this script in node, saved as example.js:
const childProcess = require('child_process');
childProcess.spawn('vim', ['-u NONE', 'test.txt'], { stdio: 'inherit' });
I would expect that node example.js would be (roughly) equivalent to calling:
vim -u NONE test.txt
However, when I execute the script I get:
$ node example.js
VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Dec 26 2020 07:37:17)
Garbage after option argument: "-u NONE"
More info with: "vim -h"
Running vim -u NONE example.txt directly works just fine.
Am I misunderstanding / misusing spawn somehow?
Edit:
This, without the -u NONE flag, works just fine:
childProcess.spawn('vim', ['test.txt'], { stdio: 'inherit' });
It's adding -u NONE that for some reason vim doesn't like.
This should work
const cp = spawn('vim', ['test.txt'], {stdio: ['inherit']})
cp.stdout.pipe(process.stdout)
Spawn open a child_process which is attached to the const cp(in this ex), this method stream its output (https://nodejs.org/dist/latest-v14.x/docs/api/child_process.html), so we need to consume it. We pipe the cp.stdout to the parent_process process.stdout. That open a new tty within: the child_process.stdout
We can make it more straightforward by setting the stdio childProcess.output option to 'inherit' and(optional) forwarding the childProcess.stderr to its own childProcess.stdout (which is already inherit by the motherProcess, so will be output automatically).
This should output the same as previously
const cp = spawn(
'vim', ['test.txt'],
{stdio: ['inherit', 'inherit', process.stdout]}
)
To run precisely the command vim -u NONE file.ext. The first argument is the executable path and the second is an array containing the flags to pass to the command. Inside this array each single element(separate with space) of the flags must be an element of the array. So in this case that should work
const cp = spawn(
'vim', ['-u', 'NONE', 'test.txt'],
{stdio: ['inherit', 'inherit', process.stdout]}
)
You could use it like this:
const { exec } = require("child-process");
exec('vim -u NONE example.txt', (err, stdout, stderr) => {
if (err) {
console.error(err);
return;
}
console.log(stdout);
});
I would like to run 2 commands with nodeJS in the same shell. However, the documentation seems that it can only run a single command child_process.spawn(command[, args][, options])
The reason 2 commands have to be executed in the same shell is because the first script would write into the environment and the second script will read from it.
This is an example of the script but I would like both ps and grep to be in the same shell.
const { spawn } = require('child_process');
const ps = spawn('ps', ['ax'], { shell: true });
const grep = spawn('grep', ['ssh'],{ shell: true });
Try
ps.stdout.pipe(grep.stdin);
I'm writing a small utility tool for development to sync files over ssh. Normally I use ssh-agent set up in .bashrc file to connect to my dev server easily. I'd like to use exec in the script, but calling ssh-agent, every time I make a request sounds a bit inoptimal.
Is there a way I could execute the agent code once, and then have it working for all subsequent ssh requests I make? E.g. to spawn a shell process like a terminal emulator, and then use that process to execute a command, rather than invoking a new shell with each command.
The reason I want to do this, is I don't want to store the password in a config file.
You can create one ssh process, and then execute other commands using same process. Here is an example how to use it for bash. I'm creating a new bash shell and execugte the command ls -la and exit you can execute other commands.
const cp = require("child_process")
class MyShell {
constructor(command) {
this._spawned = cp.spawn(command, {
stdio: ["pipe", "pipe", "inherit"],
})
}
execute(command, callback) {
this._spawned.stdin.write(command + "\n")
this._spawned.stdout.on("data", (chunk) => {
if (callback) {
callback(chunk.toString())
}
})
}
}
var myShell = new MyShell("bash")
myShell.execute("ls -la", (result) => {
console.log(result)
})
myShell.execute("exit")
Question
Is it possible to do the following?
open a new cmd.exe or terminal (on MacOS / Linux) window
pass / run a command, e.g. cd <path>
Problem
I can open cmd by running this command:
"$electron.shell.openItem('cmd.exe')"
But shell.openItem doesn't allow to pass the arguments / commands.
I tried using child_process but I couldn't make it work at all, it doesn't open a new terminal window:
const { spawn, exec } = require('child_process');
spawn('C:/Windows/System32/cmd.exe');
I also tried running the following command, but still nothing:
spawn( 'cmd.exe', [ '/c', 'echo ASDASD' ], { stdio: [0, 1, 2] } )
The only possible solution that I see is to create a command.bat:
start cmd.exe /K "cd /D C:\test"
And then use openItem:
"$electron.shell.openItem('command.bat')"
But that would only work on Windows
Solution
I finally found a way to do it on Windows:
var child_process = require('child_process');
child_process.exec("start cmd.exe /K cd /D C:/test");
Notes
You have to add the word start to open a new command window
Instead of cd /D C:/test you can specify any other command, e.g. python
/D is to make sure it will change the current drive automatically, depending on the path specified
/K removes the initial message
Don't use execSync it will lock the app until the terminal (command
prompt) window is closed
As for MacOS, looks like it's possible to do with osascript
osascript -e 'tell application "Terminal" to activate' -e 'tell application "System Events" to tell process "Terminal" to keystroke "t" using command down'
Here is a working example showing how to open a Terminal window at a specific path (~/Desktop for instance) on macOS, from a renderer script:
const { app } = require ('electron').remote;
const atPath = app.getPath ('desktop');
const { spawn } = require ('child_process');
let openTerminalAtPath = spawn ('open', [ '-a', 'Terminal', atPath ]);
openTerminalAtPath.on ('error', (err) => { console.log (err); });
It should be easy to adapt it to any selected atPath...
As for running other commands, I haven't found a way yet...
And here is the equivalent working code for Linux Mint Cinnamon or Ubuntu:
const { app } = require ('electron').remote;
const terminal = 'gnome-terminal';
const atPath = app.getPath ('desktop');
const { spawn } = require ('child_process');
let openTerminalAtPath = spawn (terminal, { cwd: atPath });
openTerminalAtPath.on ('error', (err) => { console.log (err); });
Please note that the name of the terminal application may be different, depending on the Linux flavor (for instance 'mate-terminal' on Linux Mint MATE), and also that the full path to the application can be explicitly defined, to be on the safe side:
const terminal = '/usr/bin/gnome-terminal';
HTH...
How to exec continuously? e.g. ls after cd?
I tried
exec = require('child_process').exec;
exec('cd ~/',
function(){
exec('ls'),
function(err, stdout, stderr){
console.log(stdout); // this logs current dir but not ~/'s
}
}
)
exec('cd ~/').exec('ls', function(err, stdout, stderr){
console.log(stdout);
})//this also fails because first exec returns a ChildProcess Object but not itself.
It is not possible to do this because exec and spawn creates a new process. But there is a way to simulate this. You can start a process with exec and execute multiple commands in the same time:
In the command line if you want to execute 3 commands on the same line you would write:
cmd1 & cmd2 & cmd3
So, all 3 commands run in the same process and have access to the context modified by the previous executed commands.
Let's take your example, you want to execute cd ../ and after that to execute dir and to view the previous directory list.
In cmd you shoud write:
cd../ & dir
From node js you can start a process with exec and to tell it to start another node instance that will evaluate an inline script:
var exec = require('child_process').exec;
var script = "var exec = require('child_process').exec;exec('dir',function(e,d,er){console.log(d);});";
script = '"'+script+'"';//enclose the inline script with "" because it contains spaces
var cmd2 = 'node -e '+script;
var cd = exec('cd ../ &'+cmd2,function(err,stdout,strerr)
{
console.log(stdout);//this would work
})
If you just want to change the current directory you should check the documentation about it http://nodejs.org/api/child_process.html#child_process_child_process_exec_command_options_callback
You can use nodejs promisify and async/await:
const { promisify } = require('util');
const exec = promisify(require('child_process').exec);
export default async function () {
const cpu = await exec('top -bn1');
const disk = await exec('df -h');
const memory = await exec('free -m');
const payload = {
cpu,
disk,
memory,
};
return payload
}
If you want to use cd first, better use process.chdir('~/'). Then single exec() will do the job.
You can call exec with cwd param like so:
exec('ls -a', {
cwd: '/Users/user'
}, (err, stdout) => {
if (err) {
console.log(err);
} else {
console.log(stdout);
}
})
But beware, cwd doesn't understand '~'. You can use process.env.HOME instead.