Permission Commands

groupadd group_name     //create a new group
groupdel group_name     //delete the group
cat /etc/group     //list the group
chgrp group_name file_name     //change the group
usermod -g group_name user_name     //assign the group
chmod u+x file_name     //grant user excute permission
chmod g-r file_name     //revoke group read permission
chmod o+w file_name     //grant other user write permission
umask     //check umash value
chmod 755 file_name     //set rwx rx rx permission
chmod -R 755 file_name     //set rwx rx rx permission with sub directories
chown user_name file_name     //change the file owner
chown -R user_name file_name     //change the file owner with sub directories
chown -R user_name:group_name file_name     //change owner & group with sub directories
chown -R user_name. file_name     //change same name for owner & group with sub directories