What does chmod 654 stand for?

Answer 1

chmod is a utility that allows you to change the file permissions. The octal value 654 equals to -rw-r-x-r-- (or drw-r-x-r-- if it's a directory). This means that the file owner can read and write to the file (but not execute), users in the file's group can read and execute (but not write), while for everyone else it's read-only.

Explanation

• The "read" permission is assigned the value of 4
• The "write" permission is assigned the value of 2
• The "execute (program)" permission is assigned the value of 1
• A "revoked" or "rejected" permission has the value of 0

You add these up according to what permissions are granted, except if the permissions for any one of the following categories are revoked or rejected (e.g. 000[probably not practical or possible] = nobody can access the file).

• There are 3 digits, and the first digit is for owner, the second is for group, while the last one is for all.