Chmod Calculator - Linux File Permissions Grid
Instead of memorizing octal codes, check Read, Write, and Execute for Owner, Group, and Public - Dokall instantly shows the octal value, symbolic notation, and a ready-to-paste chmod command.
Common presets include 755 for web directories, 644 for files, 600 for SSH keys, and 400 for read-only PEM keys. Edit the filename field to customize the terminal command before copying.
Frequently Asked Questions
What is chmod?
chmod (change mode) is a Unix/Linux command that sets file permissions. It controls who can read, write, and execute a file - the owner, the group, and everyone else.
What do the numbers in chmod 755 mean?
Each digit represents permissions for owner, group, and others. 7 = read(4) + write(2) + execute(1). 5 = read(4) + execute(1). So 755 means owner has full access, group and others can read and execute but not write.
What is the difference between files and directories?
Execute permission on a file means it can be run as a program. Execute on a directory means you can cd into it and list its contents. Directory permissions 755 (rwxr-xr-x) are standard; file permissions 644 (rw-r--r--) are common for regular files.
What does chmod 777 do?
777 grants read, write, and execute to everyone - owner, group, and others. This is a security risk on servers because any user can modify the file. Use 755 for directories and 644 for files unless you have a specific reason for broader access.
Symbolic vs numeric notation?
Numeric (755) is compact and common in tutorials. Symbolic (u=rwx,g=rx,o=rx) is more readable and used in chmod commands with letters: chmod u+x file adds execute for the owner. Dokall converts between both formats.