Linux Permissions

Linux permissions are set for three groups on each file or folder. The three groups are Owner, Group and World. If I open a terminal and type;

ls -la

drwxr-xr-x 44 drupalpro drupalpro  4096 Mar 27 18:03 .
drwxr-xr-x  4 root      root       4096 Jun 17  2012 ..
drwx------  3 drupalpro drupalpro  4096 Jun 22  2012 .adobe
drwxr-xr-x  8 drupalpro drupalpro  4096 Jun 22  2012 Aptana_Studio_3
-rw-rw-r--  1 drupalpro drupalpro  5188 Jun 22  2012 .bash_aliases
-rw-rw-r--  1 drupalpro drupalpro 16168 Mar 27 19:00 .bash_eternal_history
-rw-------  1 drupalpro drupalpro  6935 Mar 27 17:33 .bash_history
-rw-r--r--  1 drupalpro drupalpro   220 Jun 17  2012 .bash_logout
-rw-r--r--  1 drupalpro drupalpro  3486 Jun 17  2012 .bashrc
drwx------ 12 drupalpro drupalpro  4096 Mar 27 16:31 .cache
drwxr-xr-x  7 drupalpro drupalpro  4096 Mar 12 07:09 commerce_kickstart
drwxrwxr-x  7 drupalpro drupalpro  4096 Mar 26 16:40 commons

So looking at the last one on the list we see  the first part of the listing drwxrwxr-x give the permissions for the directory commons. The permissions work from left to right in this order ( Owner, Group and World). What this tells us is that its a directory (drwxrwxr-x) and that the owner  has rwx permissions (read,write,execute), the group has rwx permissons  (read,write,execute) and the world has r-x (read,execute).

 

 

Linux File Permissions
Octal Decimal Permission  
000 0 (0+0+0) no permission ---
001 1 (0+0+1) execute --x
010 2 (0+2+0) write -w-
011 3 (0+2+1 write and execute -wx
100 4 (4+0+0) read r--
101 5 (4+0+1) read and execute r-x
110 6 (4+2+0) read and write rw-
111 7 (4+2+1) read and write and execuute rwx