Bash/Unix/Mac - File permissions

File permissions - Bash/Unix/Mac

Format is 421

4 - read

2 - write 

1 - execute

The following table shows each permission is assigned a value.

Number	Octal Permission Representation	Ref
0	No permission	---
1	Execute permission	--x
2	Write permission	-w-
3	Execute and write permission: 1 (execute) + 2 (write) = 3	-wx
4	Read permission	r--
5	Read and execute permission: 4 (read) + 1 (execute) = 5	r-x
6	Read and write permission: 4 (read) + 2 (write) = 6	rw-
7	All permissions: 4 (read) + 2 (write) + 1 (execute) = 7	rwx

$ chmod 755 filename.txt

$ chmod 622 filename2.txt

$ chmod 

Shows how much memory is free

$ watch free -h