Linux, allows multiple users to work on the same server simultaneously without disrupting each other.
Linux File Ownership
Every file and directory on the Linux system is assigned 3 types of owner: user, group and other.
Linux File Permissions
Every file and directory in the Linux system has three permissions that are read, write and execute for three owners(user, group and other).
*To see the permission of a file or directory we use the command ls -ltr
* To change the Permission of a file or directory we use chmod <permisson type> <file name>
Let's understand the above image:
the first ‘–‘ shows that we have selected a file
-rwxrwxrwx
if there is a 'd' it determines that it is a directory
for example drwxrwxrwx
*In case we want to change the group owner only, the command is
chgrp group_name filename
For a better understanding please go through the below image :
ACL :
ACL means Access Control List. ACL allows us to give permissions for any user or group to any disc resource.
Note: chmod is use to give the permission on files or folders where ACL give permission on a file more than one group or users from diffrent groups and we can customise the permissions type.
The getfacl command is used to display the current ACL settings for a file or directory, while the The setfacl command is used to add or modify an ACL.
getfacl :
setfacl :
To add permissions for a user (user is either the user name or ID):
# setfacl -m "u:user:permissions"
To add permissions for a group (group is either the group name or ID):
# setfacl -m "g:group:permissions"
To allow all files or directories to inherit ACL entries from the directory it is within:
# setfacl -dm "entry"