Linux / unix systems are much more secure compared with Windows and allow for a very fine-grained level of access to resources. This article demystifies the linux filesystem permissions system.

# show file permissions.
$ ls -l /path/to/file

Permissions will look something like this

drwxrwxr-x

This can be split into four sections.

d        rwx       rwx         r-x
|         |         |           |
Type    Owner     Group     Other Users

Type: d means directory. In case of file, it will be -

	Meaning	Binary Reference
r	Read	4
w	Write	2
x	Execute	1

Settings Permissions

# update file permissions.
$ chmod 640 /path/to/file

6 = 4+2 (i.e. Read+Write) - Owner 4 = 4 (i.e. Read only) - Group 0 = No permissions - Other users.

Gain full access to directory

$ sudo chmod -R a+rq /path/to/file/or/directory