1. File permission:

ls -l 

The above command is displaying the file permission contents.

Its including the three stages:

Read Permission.

Write Permission.

Execute  Permission.

Four symbols are used when displaying the file permissions:

1. r: Permission to read a file and listing to a directories contents.

2.w:Permission to write a file and creating, removing file from a directories.

3.E:Permission to executing a program and changing the directory and long listing contents also there.
4.:- NO permission( in place of r , w and E).

The Group member and owner are accessing the file permission . other's can't accessing the permission.

Creating file Command: vi file name::

Creating empty file Command: touch file name::

Setting file permissions:

1.Creating file:

[student@station ~]$ touch work

2.Displaying the file permission:

[student@station ~ ]$ ls -l

3. Numeric  notation   is most efficient  to set all three permissions at once

[student@station ~ ]$ ch-mod 640 work

[student@station ~ ]$ ls -l work 

[student@station ~ ]$ -rw-r-----1 student student 

4.The numeric notation is guided to efficient way to make a change.

[student@station ~ ]$ ch-mod g-r work

[student@station ~ ]$ ls -l work

Because its displaying the make change of numeric notations