Friday, March 14, 2008

Linux Permissions

In linux, file, folder, etc can accesse by three types of user groups.

  1. Owner
  2. Group
  3. Other

and each user group has three types of permissions. read,write, and execute. As an example, (if user has read permision we denote it by using 1 and if not by 0 in binary )

Owner Group Other

rwx    rw-      r--
 111     110     100
 7         6          4

we can use "ls -l" command to view files,folders,links with permissions.

drwxr-xr-x 2 melick melick 4096 2008-11-23 00:32 Music

this is the sample. so we look each and every element further.


first charactor "d" is for type of the file. there are three types.

  • d = directory (folder)
  • l = link (symbolic link, shortcut)
  • - = file
  • c = charactor device (ex:- /dev/ttys0) {try:- ls -l /dev/ttys0}
  • b = block device (ex:- /dev/sda1)     {try:- ls -l /dev/sda1}
now we consider the permission set in the above folder.

rwxr-xrx- = rwx   r-x        r-x

  owner  group   other
  111       101       101 
 7           5          5   

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