execute a terminal command using node.js

Question

Iam trying to execute a terminal command using node.js spawn

tshark -i 3 -Y "ipp contains 02:00:00:00" -T pdml > ggggg.xml

for that am using the code

var args = ['-i', '3',
              '-Y',         
             "ipp contains 02:00:00:00" ,'-T','pdml','>','ggggg.xml'];
 

console.log(args)

var child = spawn("tshark", args, {cwd: workDir});
        child.stdout.on('data', function(data) {
          
          console.log(data.toString())        
        });
      
        child.stderr.on('data', function(data) {
          console.log('stdout: ' + data);
           
        });

        child.on('close', function(code) {
          console.log('closing code: ' + code);
              
        });

But it treated greater than >as string">" and getting output as

tshark: Invalid capture filter "> gggggg.xml" 
    
    That string isn't a valid capture filter (syntax error).
    See the User's Guide for a description of the capture filter syntax.

How can i use > without string

'> ggggg.xml' is shell syntax for redirecting stdout to file. You should use proper options of spawn nodejs.org/api/child_process.html#child_process_options_stdio or use child_process.exec which will call shell. — Alexey Ten
– Alexey Ten, Commented Feb 10, 2015 at 7:51
Does this answer your question? Running a shell command from Node.js without buffering output — Karl Knechtel
– Karl Knechtel, Commented Mar 4, 2024 at 20:37

Psl · Accepted Answer · 2015-02-11 10:11:09Z

2

You can use file streams to put all output from spawned hark to g.xml.
Example:

// don't need ">" in args
var args = [' 02:00:00:00' ,'-s','pdml'],
    logStream = fs.createWriteStream('./xml');

var spawn = require('child_process').spawn,
    child = spawn('tshark', args);

child.stdout.pipe(logStream);
child.stderr.pipe(logStream);

child.on('close', function (code) {
    console.log('child process exited with code ' + code);
});

Because of child here is a stream, you can just pipe it into your logged file stream.

edited Feb 11, 2015 at 10:11

Psl

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answered Feb 10, 2015 at 8:07

Ruslan Ismagilov

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6 Comments

Psl Over a year ago

yes one more thing..ur coding is working..but it did not output the valid xml file....some attributes are missing

Ruslan Ismagilov Over a year ago

Try to play with options: nodejs.org/api/fs.html#fs_fs_createreadstream_path_options

Psl Over a year ago

I will get the full xml file when i manully exit the running terminal using ctrl+C ..but in code i tried to exit the process and killed the child process but not getting the full output in that case also

Ruslan Ismagilov Over a year ago

Tried using 'exit' event instead of 'close' for child?

Psl Over a year ago

But it does not goes inside 'exit' event or 'close' event..that is the main problem..also i cannot identify the process is completed or not and i quil the terminal by ctrl+c command

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