chmod 444 (r--r--r--)

What chmod 444 means

Check that each class has only the access it needs (principle of least privilege).

chmod 444 file.txt          # one file
find /var/www -type f -exec chmod 444 {} +   # all files in a tree

How octal permissions work

Each digit is the sum of read (4), write (2) and execute (1) for owner, group and others. So 7 = 4+2+1 = rwx, 5 = 4+1 = r-x, 4 = r--. An optional leading digit sets special bits: setuid (4), setgid (2) and sticky (1) — e.g. 1777 is /tmp.

Safe defaults for web servers

• Directories: 755
• Files: 644
• Secrets (.env, SSH keys): 600
• Laravel storage/ and bootstrap/cache/: 775 with the web server group — never 777.

Popular modes

• chmod 777
• chmod 755
• chmod 750
• chmod 700
• chmod 666
• chmod 664
• chmod 660
• chmod 644
• chmod 640
• chmod 600
• chmod 555
• chmod 544
• chmod 500
• chmod 444
• chmod 440
• chmod 400
• chmod 775
• chmod 770
• chmod 711
• chmod 000