[node.js] executing a bash script from node.js

[Jose G. Quenum]

Hi all,
I am trying to execute bash scripts from within node.js But I am getting a Broken pipe error.

Suppose I have the following bash script
#! /usr/bin/env bash
echo $1
dir_var="/Users/username/Desktop"
new_dir="node_shell"
echo "Changing to Desktop directory"
cd $dir_var

echo "Creating a new folder"
mkdir -p $new_dir

and I execute the script with the following method

create_fs_account_1: (user_name, callback) ->
console.log "Calling script execution"
sh = spawn('sh', [user_name])
fs.createReadStream('public/shell_scripts/shell_test.sh').pipe(sh.stdin)
console.log("Just read the script file")
sh.stdout.on 'data', (data) ->
console.log "New data " + data
sh.on 'exit', (code) ->
console.log "script ended with code " + code
callback code

When I execute the method I get the following error

node.js:134
throw e; // process.nextTick error, or 'error' event on first tick
^
Error: EPIPE, Broken pipe
at Socket._writeImpl (net.js:159:14)
at Socket._writeOut (net.js:444:25)
at Socket.write (net.js:377:17)
at [object Object].ondata (stream.js:36:26)
at [object Object].emit (events.js:64:17)
at [object Object]._emitData (fs.js:916:10)
at afterRead (fs.js:898:10)
at wrapper (fs.js:245:17)

I have also noticed that when there is no error, the script doesn't really execute. the side effect I am expecting is not there. Can somebody explain to me what I am doing wrong between the script and the node.js (coffee script) code?
thanks in advance

[Diogo Resende]

1. You should avoid coffee script, at least on this ml (my opinion).
For me is more difficult to debug because I don't know the syntax.

2. Why don't you spawn the script?
> span('sh', [ 'public/....', user_name ])

3. Why do you cd to $dir_var if you mkdir -p?
> mkdir -p $dir_var/$new_dir

Hope it helps :)

---
Diogo R.

[Isaac Schlueter]

If you spawn sh, it wont' be a login shell, so this isn't going to
work as you expect.

It'd be better to do something like this:

spawn("bash", ["public/shell_scripts/shell_test.sh"])

or even:

spawn("bash", ["public/shell_scripts/shell_test.sh"],
{ cwd: "/Users/username/Desktop", uid: <username uid> })

(And yes, you'll get better responses if you post examples in native
js rather than a to-js language.)

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[Jose G. Quenum]

thanks to y'all for your comments. The script I use in this example is just a dummy stuff to test how to execute bash scripts in node.js. The actual scripts will be ssh commands.

Anyway, let me compile my code in javascript and get back to the group

[Isaac Schlueter]

On Sun, Oct 9, 2011 at 14:50, Jose G. Quenum <ghis...@gmail.com> wrote:
> thanks to y'all for your comments. The script I use in this example is just a dummy stuff to test how to execute bash scripts in node.js. The actual scripts will be ssh commands.

Note that ssh takes an argument which is the command to run on the
remote server, so you could do this pretty easily in the same way.

spawn("ssh", ["user@remotehost", "chdir blah && ls"])

[Jose G. Quenum]

changing from sh to bash solves the broken pipe problem. But, still the script as it is doesn't execute. I don't see the folder being created in Desktop. Is there something wrong in the way I call the script?

[Ryan Schmidt]

On Oct 9, 2011, at 16:50, Jose G. Quenum wrote:

> The actual scripts will be ssh commands.

In that case, you might be interested in existing modules for dealing with ssh, like:

https://github.com/FlashFan/NodeSSH

[Jose G. Quenum]

cool thanks @ryan. I'll take a look at it as soon as I am done with my tests.
Right now I am still struggling with getting node to execute a simple script.

[Floby]

what is this supposed to do?
fs.createReadStream('public/shell_scripts/
shell_test.sh').pipe(sh.stdin)

[Damianos Mylonakis]

Create a Readable Stream (async, non-blocking) and when data chunks are available, pipe them to stdin of the spawned process.
pipe is just a proxy. When the data event of the readable stream is fired, it will do sh.write(data).