Understanding File Permissions
I thought this might help and add to the knowledge base of our subforums. This is a basic, roughly pieced together reference. So, some of you may have noticed mention of setting file permissions to 644, for example (or 755). This format of file permissions is called CHMOD (short for "change mode"). It determines how much access a file should have. For the sake of simplicity, I'll leave it at that.
I'll go over what each digit (1-7) represents, which is some variation/combination of having read, write, or execute permissions. In Root Explorer, for example, there are three lines - Owner, Group, and Others. In file permissions, the three digits represent the permissions allowed for the aforementioned Owner, Group, and Others. The first digit represents Owner, the second digit represents Group, and the last represents Others.
Owner - 6
Group - 4
Others - 4
*644 is also referred to as rw-r-r (i.e., read and write permissions for Owner, read only permissions for Group, and read only permissions for Others).
Here's what each number is the equivalent to:
0 - No Permissions
1 - Execute Only
2 - Write Only
3 - Write and Execute Permissions
4 - Read Only
5 - Read and Execute Permissions
6 - Read and Write Permissions
7 - Read, Write, and Execute Permissions
Most system files have permissions of rw-r-r/644, while scripts have 755.