permissions using access control list

Pranaam to all bhai ji _/\_
Today we are going to learn about access control  list (ACL) , which is used for specifying permission on a file for a particular user only .
we have gone through read/write/execute file permissions in article http://www.mannulinux.org/2013/08/file-permissions-in-linux.html .
ACL differs from normal file permission implementation .
in normal file permission we can set permission for owner , user in a group associated with that file and for rest of the user on the system. but in case we want to set some specific permission for a user only (not for the group or rest or the user), we need to use access control list .

for example we have a file whose owner and group is root and 'other' user has only read permission but  want to issue execute permission to a user which is neither owner nor in group of the file and exist in other user category . i also dont want to let other user to execute that file other then specific user
lets start .......
this is how current configuration

and i want to set permissions for file cmd.sh, whose default permissions are

for checking current permissions on file (including access control list permissions)
we use command
 getfacl filename
getfacl stands for  get file access control list
filename is the name of the file for which we are checking permissions (it may be full path too)

permissions are following

to set access control list, we use command
setfacl options file
To get full list of options that we can use with setfacl command , type setfacl --help

file cmd.sh has read,write and execute permissions for its owner(root) , read and execute permissions for group(root) and read only permission for other user
now we are going to set permissions for file cmd.sh in such way , user indishell belogs to other user category but it will have read and execute permissions
lets have a look on command
setfacl  -m u:indishell:r-x  cmd.sh 
this command will modiffy permissions for user indishell and will set them as read and execute for file cmd.sh

ok , now we will confirm whether user indishell is able to execute file or not .
loging in to user account indishell

user indishell is neither root user nor in group 'root'
file permissions for cmd.sh

indishell user is in other user category and other user dont have permission to execute file cmd.sh
we have configured ACL for file cmd.sh and user indishell should be able to execute this file
lets run command ./cmd.sh and confirm it >:D<

yesssssssss. its working fine :)

lets check whether its just for user indishell or other users too
i am switching to user account ica
it is another normal user which is exist in other user category

lets try to execute cmd.sh using this user account

:P ooops . user ica is not able to execute it
why???? lets have a look on normal file permissions as well as access control list

so we can see , ACL is working fine . lets allow user ica to edit file cmd.sh :P
command will be
setfacl -m u:ica:rw- cmd.sh

Thank you

Greetz to :-
Zero cool ,code breaker ica, Aasim shaikh,Reborn, Raman kumar rana,INX_r0ot,Darkwolf indishell, Chinmay Pandya ,Silent poison India,Magnum sniper,Atul Dwivedi,ethicalnoob Indishell,Local root indishell,Irfninja indishell,Hardeep bhai,Mannu,Viki , AR AR bhai ji, Anju and Deepika kaushik

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