Linux ACL Permissions
ACL - ACCESS CONTROL LIST
An access control list (ACL) assign permissions for each unique user or group.
We can use the setfacl and getfacl command utilities to assign and verify the ACL of a file or directory.
how to set acl permissions to a file or directry for users ,groups and other
#setfacl -m u:username:rwx,g:groupname:rwx,o:others:rwx filename or directoryname
how to chech all permissions
#getfacl filename or directoryname
how to remove acl permissions to a user
#setfacl -x u:username filename or directoryname
how to remove all acl permissions to a file or directory
#setfacl -b filename or directoryname
SUID – SET USER ID #chmod u+s or #chmod 4XXX Note: the s where x would usually indicate execute permissions for the user. If the file owner doesn't have execute permissions, then use an uppercase S here.
SGID – SET GROUP ID #chmod g+s or chmod 2XXX
STICKY BIT - If sticky bit is applied on a file or directory, then only root and owner of that file or directory can delete it. Even if others are having full permissions they cannot delete the file or directory. #chmod o+t or chmod 1XXX