Chmod Calculator
Calculate Unix/Linux file permissions with a visual editor. Convert between numeric (octal) and symbolic chmod notation instantly.
| Role | Read | Write | Execute | Value |
|---|---|---|---|---|
| Owner | 7 | |||
| Group | 5 | |||
| Others | 5 |
rwxr-xr-xchmod 755 <file>Frequently Asked Questions
What does chmod 755 mean?
chmod 755 sets the file permissions so the owner has full access (read, write, execute = 7), while the group and others have read and execute access (5). In symbolic notation, this is rwxr-xr-x. This is the most common permission for directories and executable scripts.
What does chmod 644 mean?
chmod 644 sets the file permissions so the owner can read and write (6), while the group and others can only read (4). In symbolic notation, this is rw-r--r--. This is the standard permission for regular files like HTML, CSS, and configuration files.
How do octal permission numbers work?
Each digit in the octal permission represents a role: owner, group, and others (left to right). Each digit is the sum of: read (4) + write (2) + execute (1). For example, 7 = 4+2+1 (rwx), 6 = 4+2 (rw-), 5 = 4+1 (r-x), 4 = 4 (r--).
What is the difference between chmod numeric and symbolic mode?
Numeric (octal) mode uses three digits like 755, where each digit represents permissions for owner, group, and others. Symbolic mode uses letters: r (read), w (write), x (execute), with - for no permission. For example, 755 = rwxr-xr-x. Numeric mode sets all permissions at once, while symbolic mode can modify individual permissions.
Should I ever use chmod 777?
chmod 777 gives everyone full read, write, and execute permissions, which is a security risk. It should generally be avoided on production servers. Use 755 for directories that need to be accessible and 644 for regular files. Only use 777 temporarily during development if absolutely necessary.