chmod Calculator

How to Use the chmod Calculator

This free chmod calculator helps you determine the correct Linux file permissions. Use the checkbox grid to set read, write, and execute permissions for owner, group, and other users. The numeric (octal) value and symbolic representation update automatically. You can also type a numeric value directly to see the corresponding permissions.

Understanding File Permissions

• Read (4) - View file contents or list directory contents
• Write (2) - Modify file contents or create/delete files in directory
• Execute (1) - Run file as program or access directory
• Owner - The user who owns the file
• Group - Users in the file's group
• Other - All other users

Common Permission Settings

644 (rw-r--r--) is the standard for regular files - owner can read/write, everyone else can only read. 755 (rwxr-xr-x) is standard for executables and directories - owner has full access, others can read and execute. 700(rwx------) gives only the owner access. 777 (rwxrwxrwx) gives everyone full access and should be avoided for security reasons.

How Octal Notation Works

Each digit represents permissions for one group (owner, group, other). The digit is the sum of: read (4) + write (2) + execute (1). For example, 7 means rwx (4+2+1), 5 means r-x (4+1), 6 means rw- (4+2), and 0 means no permissions. So chmod 755 sets rwxr-xr-x.

chmodパーミッション計算ツールについて

Linuxファイルパーミッションをチェックボックスで視覚的に設定できるツールです。数値(755等)とシンボリック(rwxr-xr-x)形式を相互変換し、chmodコマンドをワンクリックでコピーできます。よく使うプリセットも用意しています。