Node js check if file is being used by another process

Question

I'm working on a node-webkit app that performs filesystem operations. I need to be able to check if the file is being used by another process before deleting (unlinking).

If I only use the fs.unlink method, the system will wait until the file stops being used before removing it completely. What I want is that if the file is being used, don't wait until it's released, but cancel the whole operation and don't delete it.

Thanks.

What happen if you delete the file with a synchronous operation. Do you get an error or it blocks your script? — Krasimir, May 23 '14 at 04:11
I am stuck in a similar situation therefore, I can say that the file won't get deleted unless it is released. Releasing here also means stopping the server which is not something ideal to do. — Neeraj Sewani, Oct 27 '21 at 08:15

score 3 · Answer 1 · answered May 23 '14 at 19:20

Assuming you're on a *nix system something like this should work. Obviously this is overly simplified as far as error and path checking. There may very well be a better way to do this but I might as well start the discussion with this:

var fs = require('fs'),
    exec = require('child_process').exec;

function unlinkIfUnused(path) {
    exec('lsof ' + path, function(err, stdout, stderr) {
        if (stdout.length === 0) {
            console.log(path, " not in use. unlinking...");
            // fs.unlink...
        } else {
            console.log(path, "IN USE. Ignoring...");
        }
    });
}

unlinkIfUnused('/home/jack/testlock.txt');

Node js check if file is being used by another process

1 Answers1