access control list in linux with example.

Create required users & Group 
[root@server ~]# useradd tom 
[root@server ~]# groupadd salesgrp 
[root@server ~]# groupadd fingrp 
[root@server ~]# mkdir /salesdept 
[root@server ~]# useradd -g salesgrp sai
[root@server ~]# useradd -g salesgrp ram
[root@server ~]# useradd -G fingrp  tata
[root@server ~]# useradd -G fingrp  birla
Note: Acl's are applied on both primary & secondary  members 
Step 1 ) Create a required partition 
[root@server ~]# fdisk -l 
[root@server ~]# fdisk /dev/hda 
:n 
:w 
[root@server ~]# partprobe /dev/hda 
[root@server ~]# mkdir /salesdept 
[root@server ~]# mkfs.ext3 /dev/hda9 
Step 2) Mount the partition with user & group quota parameters. 

[root@server ~]# mount -o  acl /dev/hda9 /salesdept
[root@server ~]# mount
[root@server ~]# chmod 777 /salesdept/ 
Step 3) Apply ACLS on users & groups 
[root@server salesdept]# touch fabc.txt 
To apply acl's on users & groups 
[root@server salesdept]# setfacl -m 
u:tom:rwx,u:ram:rx,g:salesgrp:rx,g:fingrp:rw   fabc.txt 

To check acl list 
[root@server salesdept]# getfacl  fabc.txt 
To modify permission for user tom 
[root@server salesdept]# setfacl -m u:tom:r  fabc.txt 
[root@server salesdept]# getfacl  fabc.txt 
To exclude user tom ,group fingrp  from ACL list 

[root@server salesdept]# setfacl -x u:tom,g:fingrp  fabc.txt
[root@server salesdept]# getfacl fabc.txt