Linux Tool

Chmod Calculator

Calculate Linux file permissions with ease. Convert between numeric (755) and symbolic (rwxr-xr-x) notation. Understand what each permission bit means for security.

Understanding Linux Permissions

Linux file permissions control who can read (r=4), write (w=2), and execute (x=1) files. Permissions are set for three groups:

Owner - File creator
Group - Group members
Others - Everyone else
Numeric
755
Symbolic
rwxr-xr-x
Owner
Group
Others
Command
chmod 755 filename
Common Permissions
755 Scripts, directories
644 Regular files
777 Full access (risky!)
600 Private files
700 Private scripts
400 SSH keys
Security Tips
  • Avoid 777 on web servers
  • Use 600 for SSH keys
  • Scripts need execute (x)