Calculate Unix file permissions. Toggle checkboxes or use presets.
Unix file permissions control who can read, write, and execute files. Every file has three permission groups: owner (the user who created it), group (users in the file's group), and others (everyone else). Each group can have read (r), write (w), and execute (x) permissions.
Permissions are represented in two ways: symbolic notation like rwxr-xr-x (9 characters, 3 per group) and numeric/octal notation like 755. In octal, each digit is the sum of: read=4, write=2, execute=1. So 7 (4+2+1) means full access, 5 (4+1) means read+execute, and 0 means no access.
Common permission sets: 755 for executable files and directories (owner full, others read+execute), 644 for regular files (owner read+write, others read-only), 600 for private files (owner only), and 777 for full access (avoid in production — security risk). The chmod command changes permissions: chmod 755 filename.
This tool in other languages:
Français:
Calculateur chmod
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Calculadora chmod
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Chmod-Rechner
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Calculadora chmod
日本語:
chmod計算機
中文:
chmod 权限计算器
한국어:
chmod 권한 계산기
العربية:
حاسبة صلاحيات chmod
Toggle the 9 checkboxes (read/write/execute for owner/group/world) to build your permissions. The numeric (e.g. 755), symbolic (rwxr-xr-x), and full chmod command update in real-time. Click a preset like 755 or 644 for common defaults.
Owner can read, write, and execute (7 = 4+2+1). Group and world can read and execute (5 = 4+0+1) but not write. This is the standard permission for executable scripts and directories.
644 gives owner read/write, others read-only — standard for regular files. 755 adds execute permission for owner/group/world — use for executable files and directories (directories need execute to be traversable).
644 = files (owner write, others read). 755 = directories, scripts (all can execute). 600 = private config files, SSH keys (owner only). 700 = private executables. 777 = world-writable (avoid — security risk).
It lets any user on the system read, modify, and execute the file. On a shared server, any compromised account or process can alter 777 files, inject malicious code, or read secrets. Use the most restrictive permission that still works — rarely is 777 actually necessary.