Chmod Calculator

What does chmod 755 mean?

chmod 755 gives the owner full permissions (read, write, execute = 7), while group and others get read and execute permissions (5). This is commonly used for executable scripts and directories. The owner can modify the file, but others can only read and run it.

How do I make a file executable in Linux?

Run chmod +x filename to add execute permission, or use chmod 755 filename for a common executable permission set. For scripts that only you should run, use chmod 700 filename to keep it private.

What is the difference between chmod 755 and 777?

755 allows the owner to read, write, and execute, while others can only read and execute. 777 gives full permissions to everyone, which is a security risk. Use 755 for public executables and avoid 777 except for temporary testing.

What does rwx mean in file permissions?

r = read (view file contents), w = write (modify the file), x = execute (run as a program). These three permissions apply to three groups: owner, group, and others. A dash (-) means the permission is not granted.

How do I check file permissions in Linux?

Use ls -l filename to see permissions in symbolic format like -rwxr-xr-x. Use stat filename for more details including the numeric format. The first character shows the file type (- for regular file, d for directory).

What chmod should I use for web files?

For web files: use 644 for HTML, CSS, JS files (readable by web server). For directories: use 755 (web server needs execute to list contents). For PHP files that need to be run: use 644 or 755. Never use 777 on a web server.

What is the most secure file permission?

600 (rw-------) for files - only the owner can read and write. 700 (rwx------) for executables and directories - only the owner can access. Use these for sensitive files like SSH keys, configuration files with passwords, and private scripts.

How do I change permissions recursively?

Use chmod -R 755 directory/ to apply permissions to a directory and all its contents. Be careful with -R as it affects all files. For mixed content, use find command: find . -type f -exec chmod 644 {} ; for files and find . -type d -exec chmod 755 {} ; for directories.