File permission in unix is done with the help of chmod command.

Give below is the way of how to use File Permission for Unix

chmod command in unix
chmod octal file – change the permissions of file
to octal, which can be found separately for user,
group, and world by adding:
● 4 – read (r)
● 2 – write (w)
● 1 – execute (x)
Examples:
chmod 777 – read, write, execute for all
chmod 755 – rwx for owner, rx for group and world
For more options, see man chmod.

For Basic commands tutorial. Please refer to Basic commands in Unix

For Process Management tutorial. Please refer to Process Management commands in Unix