chmod Calculator

chmod 755 means the owner has read+write+execute (7), the group has read+execute (5), and others have read+execute (5). It's the standard permission for web server files and executable scripts.

Octal notation represents permissions as a 3-digit number (e.g., 755). Symbolic notation uses letters (e.g., rwxr-xr-x). Both convey the same information — the calculator shows both simultaneously.

r = read (can view file contents or list directory), w = write (can modify file or create/delete files in directory), x = execute (can run file as program, or enter directory with cd).

chmod 777 gives read, write, and execute permissions to everyone on the system. Any user or process can modify or delete the file. This is a serious security risk on shared servers — never use it for web-accessible files.

644 (rw-r--r--) for static files, 755 (rwxr-xr-x) for directories and executables, 600 (rw-------) for private keys and sensitive config files, 700 (rwx------) for private scripts.