OS X - Access Control Lists (ACL)



Every modern operating system provides a more fine graded method of access control to operating system items then the classic Unix security witch can provide read, write and execute permission to the three groups Owner, Group and Others. Mac OS X uses two types of permissions on files, file modes and Access Control Lists (ACLs).

Managing ACL's

The command s


remove acl
add acl
# specifies th rule which should be deleted or modified ACL command "user

ls -le

show ACLs

   ls -le  OSX-Acl.txt 
   -rw-r--r--+ 1 tuxi  staff  29 16 Aug 12:59 OSX-Acl.txt
    0: user:tuxi deny read,write
    1: user:tuxi allow append

area uesed to manage ACLs on OSX


Complete Sample of ACLs

In a shell type the following commands to test.

   ls -le  OSX-Acl.txt 
   -rw-r--r--+ 1 tuxi  staff  58 16 Aug 13:06 OSX-Acl.txt
    0: user:tuxi allow append

Samples using chmod for ACLs

 chmod +a "admin allow write" myfile.txt
 chmod +a "guest deny read" myfile.txt
 chmod +a "admin allow delete" myfile.txt
 chmod +ai "others allow read" myfile.txt
 chmod +a# 2 "others deny read" myfile.txt
 chmod -a# 1 myfile.txt
 chmod -a "admin allow write" myfile.txt
 chmod =a# 1 "admin allow write,chown"


Fixing "Finder wants to make changes" message

If the "Finder wants to make changes. Type your password to allow this." dialog appears when you attempt to move, rename, or delete files, it's likely incorrect permissions on your files have accidentally been set. More specifically, the Access Control Lists (ACLs) on the affected files causes the problem.
To correct the problem, you'll need to use the Terminal to remove the ACL from the problem file with the following command:
chmod -N filename

Status: Published Date: 2017/06/05 14:13:04 Revision: 1.1

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