file permissions

permissions.txt

File Permissions

   1   2   3
- --- --- ---
d rwx rwx rwx

r: Read
w: Write
x: Execute (execute file as a program, or execute directory meaning see contents of directory)
 
The starting 'd' flag determines type of file (directory, file, some other stuff i don't know)
1st part is User's permissions
2nd part is Group's permissions
3rd part is Everyone else's permissions

By default, most files are rw- r-- r-- and most directories are rwx r-x r-x


Binary notation is often used to represent permissions.
1 1 1 in binary = 4 + 2 + 1 = 7

777 is full permissions (111 111 111)
644 is default file permissions (110 100 100)
755 is default directory permissions (111 110 110)
600 is highly secure file permissions (100 000 000) e.g. SSH Private Key file