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Wednesday, 29 October 2014

Alter File Permissions in Nodejs

In this post we will show you how to alter file permissions in Nodejs. When you are planning to alter the permissions on a file, you might want to change the ownership. In Nodejs we use fs.chown to change the ownership of a file.

According to Nodejs fs.chown function accepts four arguments that are path, uid, gid, callback.

path : file you wish to perform the ownership alteration
uid : integer of the user id on your system
gid : integer of the group id to which the user belongs
callback : callback function attached with fs.chown

To determine the User and Group Id Numbers you have to use below commands in Terminal

> id -u Your_UserName
> id -g Your_UserName

To Change access mode of the file you can use fs.chmod whioch accepts three arguments that are path, mode, callback.

path : file you wish to perform the access mode alteration
mode : The integer value of the octal permission code
callback : callback function attached with fs.chmod

File Access Settings of various files are :

4000 : Hidden File
2000 : System File
1000 : Archive bit
0400 : Individual read
0200 : Individual write
0100 : Individual execute
0040 : Group read
0020 : Group write
0010 : Group execute
0004 : Other read
0002 : Other write
0001 : Other execute

Where 1 represents execute, 2 represents write and 4 represents read

Code :

var fs = require('fs');
var file = 'D:\example\example1.js';
//Hide File
fs.chmod(file, 4000, function(err)){
if(err) throw err;
//Individual Write On File
fs.chmod(file, 0200, function(err)){
if(err) throw err;
//Individual write + execute
fs.chmod(file, 0300, function(err)){
if(err) throw err;
//Individual read + write + execute (full access to an individual)
fs.chmod(file, 0700, function(err)){
if(err) throw err;
//Change Owner by root user
fs.chown(file, 0, 0, function(err)){
if(err) throw err;

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