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Weird pipe behavior in node's child_process?


Weird pipe behavior in node's child_process?

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Weird pipe behavior in node's child_process?
Tag : node.js , By : Sharad
Date : January 12 2021, 08:33 AM

should help you out The catch is in jq's attempts to intelligently infer the default filter, if the filter was omitted.
Namely, when output goes to a terminal (TTY), the filter may be omitted, and it defaults to . (pretty print). That's why in terminal you can write:
cat file | jq           # or:  jq < file
cat file | jq .         # or:  jq . file
var command = "cat /tmp/gen_json | jq .";
var command = "jq . /tmp/gen_json";

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Spawn node child_process with named pipe as stdin


Tag : node.js , By : user171752
Date : March 29 2020, 07:55 AM
wish help you to fix your issue The answer is to use fs.open and the stdio options in child_process.spawn as such:
var spawn = require('child_process').spawn;

var fd_stdin = fs.openSync('lk.log', 'r');
spawn('node', ['monitor.js'], {
    stdio: [fd_stdin, 1, 2];
});

Weird behavior of program on force closing one end of pipe


Tag : cpp , By : Valentine
Date : March 29 2020, 07:55 AM
Any of those help Your program doesn't check the return for read() and write().
Since a failed read won't fill buf with the string "exit", your break condition never occurs.

How to use the pipe option of `child_process.spawn`?


Tag : javascript , By : Ari
Date : March 29 2020, 07:55 AM
it should still fix some issue The code you have looks like it should already be attaching /dev/null to stdin, and piping stdin + stdout to respective streams of the parent process. Is that not working?
The same thing can be achieved a few different ways.
var spawn = require("child_process").spawn;

var ls = spawn("ls -a");
ls.stdout.pipe(process.stdout);
ls.stderr.pipe(process.stderr);
ls.on("exit", function(code) {
    process.exit(code);
});

Using a pipe character | with child_process spawn


Tag : node.js , By : FarmerDave
Date : March 29 2020, 07:55 AM
should help you out This has been answered in another question: Using two commands (using pipe |) with spawn
In summary, with child.spawn everything in args should be an argument of your 'raspivid' command. In your case, the pipe and everything after it are actually arguments for sh.
 var args = ['-c', <the entire command you want to run as a string>];

How do i pipe a long string to via child_process.spawn() in Node.js?


Tag : node.js , By : Maplye
Date : March 29 2020, 07:55 AM
To fix this issue pdftotext should allow reading from stdin and writing to stdout (at least it worked for me with v0.41.0), so you could do this instead:
S3Fs.readFile('./my-pdf-in-s3-bucket', (err, result) => {
  if (err) throw err; // Handle better
  var cp = child_process.spawn('pdftotext', [ '-', '-' ]);
  cp.stdout.pipe(process.stdout);
  cp.on('close', (code, signal) => {
    console.log(`pdftotext finished with status ${code}`);
  });
  cp.stdin.end(result);
});
var cp = child_process.spawn('pdftotext', [ '-', '-' ]);
var rs = S3Fs.createReadStream('./my-pdf-in-s3-bucket');
rs.on('error', (err) => {
  cp.kill();
});
cp.stdout.pipe(process.stdout);
cp.on('close', (code, signal) => {
  console.log(`pdftotext finished with status ${code}`);
});
rs.pipe(cp.stdin);
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