Never really understood what was going on with Linux File Permissions and chmod?
If you understand binary then this will be a piece of cake. Here is a simple blog post to demystify Unix File Permissions:
Ever seen:
-rwxr-xr-- 1 dgerman staff 823 Dec 16 15:03 findPhoneNumbers.sh
Operations:
- r – Read
- w – Write
- x – Execute
Now why are there 3 sets of rwx?
- User – The owner of the file
- Group – The group owning the file
- Others (Rest of the World) – anyone
Below is a table Showing numeric permissions.
| # | Permission | rwx |
|---|---|---|
| 7 | read, write and execute | 111 |
| 6 | read and write | 110 |
| 5 | read and execute | 101 |
| 4 | read only | 100 |
| 3 | write and execute | 011 |
| 2 | write only | 010 |
| 1 | execute only | 001 |
| 0 | none | 000 |
When you give a 777 permission to a file/folder, you are giving user, group and anyone ((20 x 1 + (21 x 1 + 22 x 1)) = 7. That is Read, write and Execute.