Unix File system Permissions

Hey Guys,

Today i will explain about the Linux file permissions that i learned.

So, In short it consists of three access permissions for below list

1. user/owner(u)
2. group(g)
3. outside world(o)

and permissions are

1. read(r)
2. write(w)
3.execute(x)

So, when you do ls -l , it displays the list of files under directory . it will be displayed like filename with -drwx---

Lets expand above structure:

• -: "regular" file, created with any program which can write a file
• b: block special file, typically disk or partition devices, can be created with mknod
• c: character special file, can also be created with mknod (see /dev for examples)
• d: directory, can be created with mkdir
• l: symbolic link, can be created with ln -s
• p: named pipe, can be created with mkfifo
• s: socket, can be created with nc -U
• D: door, created by some server processes on Solaris/openindiana.

Here is the linux file permission overview. image from stack exchange

Numerical permissions

#	Permission	rwx
7	read, write and execute	rwx
6	read and write	rw-
5	read and execute	r-x
4	read only	r--
3	write and execute	-wx
2	write only	-w-
1	execute only	--x
0	none	---

Unix Permission Calculator :

http://permissions-calculator.org/