chmod – change file/folder permission in ubuntu

sample command:

 sudo chmod 754 /opt/lampp/htdoc

chmod command sets the permission of a file or folder. chmod command uses three digit code as an argument and the file or folder location.

In the example,

• 7 – Owner(current user)
• 5 – Group(set by owner)
• 4 – anyone else

The fundamental concept:

Execute is 1, Write is 2 and Read is 4.

Sum of these basic ones makes combination of permissions:

• 0 – no permission, this person cannot read, write or execute
• 1 – execute only
• 2 – write only
• 3 – execute and write only (1 + 2)
• 4 – read only
• 5 – execute and read only (1 + 4)
• 6 – write and read only (2 + 4)
• 7 – execute, write and read (1 + 2 + 4)

source: online