CODEWITHSUNDEEP
node.jsfilesystems
Drew LeSueur
Drew LeSueur

Reputation: 20145

How do I check if a file is executable in node.js?

How do I check if a file is executable in node.js?

Maybe something like

fs.isExecutable(function (isExecutable) {

})

Upvotes: 12

Views: 8712

Answers (6)

Ciro Santilli OurBigBook.com
Ciro Santilli OurBigBook.com

Reputation: 383708

fs.stat named bitmask mode check with fs.constants.S_IXUSR

Node.js appears to have added those since https://stackoverflow.com/a/16258627/895245 had been written, you can now do:

const fs = require('fs');

function isExec(p) {
  return !!(fs.statSync(p).mode & fs.constants.S_IXUSR)
}

console.log(isExec('/usr/bin/ls'))
console.log(isExec('/dev/random'))

Of course, this highlights the fact that it is a bit harder to do an actual "can I execute this file check", since we have three such constants as documented at https://nodejs.org/docs/latest-v17.x/api/fs.html#file-mode-constants:

  • fs.constants.S_IXUSR: user
  • fs.constants.S_IXGRP: group
  • fs.constants.S_IXOTH: other

as per:

man 2 chmod

so a full check with stat requires checking if you match the file owner, or are part of a group.

So perhaps it is better to just use the cumbersome raise API of fs.accessSync as mentioned athttps://stackoverflow.com/a/41929624/895245 which actually checks if the current user could execute a given file or not:

const fs = require('fs');

function isExec(p) {
  try {
    fs.accessSync(p, fs.constants.X_OK)
    return true
  } catch (e) {
    return false
  }
}

console.log(isExec('/usr/bin/ls'))
console.log(isExec('/dev/random'))

which should be doing all those checks for us.

Upvotes: 4

TamusJRoyce
TamusJRoyce

Reputation: 834

This version is a little more fully featured. But it does rely on either which or where, which are os specific. This covers Windows and Posix (Mac, Linux, Unix, Windows if Posix layer exposed or Posix tools installed).

const fs = require('fs');
const path = require('path');
const child = require("child_process");

function getExecPath(exec) {
  let result;
  try {
    result = child.execSync("which " + exec).toString().trim();
  } catch(ex) {
    try {
      result = child.execSync("where " + exec).toString().trim();
    } catch(ex2) {
      return;
    }
  }
  if (result.toLowerCase().indexOf("command not found") !== -1 ||
      result.toLowerCase().indexOf("could not find files") !== -1) {
    return;
  }
  return result;
}    


function isExec(exec) {
  if (process.platform === "win32") {
    switch(Path.GetExtension(exec).toLowerCase()) {
      case "exe": case "bat": case "cmd": case "vbs": case "ps1": {
        return true;
      }
    }
  }
  try {
    // Check if linux has execution rights
    fs.accessSync(exec, fs.constants.X_OK);
    return true;
  } catch(ex) {
  }
  // Exists on the system path
  return typeof(getExecPath(exec)) !== 'undefined';
}

Upvotes: 1

Danny Guo
Danny Guo

Reputation: 1022

Another option that relies only on the built-in fs module is to use either fs.access or fs.accessSync. This method is easier than getting and parsing the file mode. An example: 

const fs = require('fs');

fs.access('./foobar.sh', fs.constants.X_OK, (err) => {
    console.log(err ? 'cannot execute' : 'can execute');
});

Upvotes: 19

user619271
user619271

Reputation: 5022

Take a look at https://www.npmjs.com/package/executable it even has a .sync() method

executable('bash').then(exec => {
    console.log(exec);
    //=> true 
});

Upvotes: 2

Daniel
Daniel

Reputation: 38821

You would use the fs.stat call for that.

The fs.stat call returns a fs.Stats object.

In that object is a mode attribute. The mode will tell you if the file is executable.

In my case, I created a file and did a chmod 755 test_file and then ran it through the following code:

var fs = require('fs');
test = fs.statSync('test_file');
console.log(test);

What I got for test.mode was 33261.

This link is helpful for converting mode back to unix file permissions equivalent.

Upvotes: 9

gongzhitaao
gongzhitaao

Reputation: 6682

In Node the fs.stat method returns an fs.Stats object, you can get the file permission through the fs.Stats.mode property. From this post: Nodejs File Permissions

Upvotes: 2

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