Convert file permissions to CHMOD octal values
CHMOD (Change Mode) sets file permissions using octal numbers. Each digit represents owner, group, and public permissions. Values are calculated by adding: Read(4) + Write(2) + Execute(1).
Owner can read, write, execute (4+2+1=7). Group can read, execute (4+1=5). Public can read, execute (4+1=5). Common for web directories.
Owner read/write (4+2=6). Group read (4). Public read (4). Secure for regular files.