ACLs

Granting rwx access to files and directories for one or more users or groups.

Inorder to enable ACLs on a file system, the filesystem must be mounted with acl mount option.Filesystems created during installation include the acl flag in their default munt option.To remount a file system eg:/ home with acl option, run the following:
mount -o remount,acl /home

To view the acl for a file use getfacl:

ls -l fork2.pl
-rwxrwx---  1 sriram sriram 352 Aug  2 17:40 fork2.pl
getfacl  /home/sriram/ fork2.pl
# file: fork2.pl
# owner: sriram
# group: sriram
user::rwx
group::rwx
other::r-x
To enable other user named "varun" to execute fork2.pl whose owner if sriram, use setfacl:

setfacl -m u:varun:rwx fork2.pl

getfacl fork2.pl
# file: fork2.pl
# owner: sriram
# group: sriram
user::rwx
user:varun:rwx
group::rwx
mask::rwx
other::---
Now, user "varun" can execute the file "fork2.pl" :
[root@localhost sriram]# su - varun
[varun@localhost sriram]$ ./fork2.pl
[varun@localhost sriram]$

Examine the permissions of  fork2.pl :

[varun@localhost sriram]$ ls -l fork2.pl
-rwxrwx---+ 1 sriram sriram 352 Aug  2 17:40 fork2.pl
There is a "+" sign at the end of the permission bits indicating  that fork2.pl is accessable by an non-member user.