All About Permissions
To begin with file permissions in linux are way to controll who can access what? generally this comprises of following file permissions
read(r) → who can view
write(w) → who can modify
execute(c) → who can execute
Now each file has a set of three pople accessing it owner-group-others ex. .rw-r--r-- this means owner has read and write while group and others has read permissions.
you can check file permissions using ls -l or getfacl filepath for more details. we can modify the files using octal code and chmod command.
| Permission | Octal bit |
|---|---|
| r | 4 |
| w | 2 |
| x | 1 |
looking at above table the addition or removal of those will determine permisson example 755. This means all have execute and read permissions. only owner has write permission.
7 → 4+2+1 → owner → read-write-execute
5 → 4+0+1 → group → read-execute
5 → 4+0+1 → others → read-execute
information of representation
0 → no permissions
1 → execute
2 → write
3 → write-execute
4 → read
5 → read-execute
6 → read-write
7 → read-write-execute
Take look at below example
644 => .rw-r--r-- => read-write to owner. read group and others
655 => .rw-r-xr-x => read-write to owner. read-execute to group and other
777 => .rwxrwxrwx => every permission to everyone
766 => .rwxrw-rw- => all for owner and read-write for group-others
600 => .rw------- => only owner can read and write
700 => .rw------- => only owner can read-write-execute