Read
Write
Execute
Owner
Group
Other
Octal
755
Symbolic
rwxr-xr-x
Command
chmod 755 file
Octal → Checkboxes
About this tool
Unix file permissions control who can read, write, and execute a file or directory. The three permission groups are Owner (the user who owns the file), Group (members of the file's group), and Other (everyone else). Each group has three bits - read (4), write (2), execute (1) - and their sum gives a single octal digit. The common 755 (rwxr-xr-x) makes a file executable by everyone but only writable by its owner. For web server files, 644 is standard for content files and 755 for directories. Avoid 777 (world-writable) in production environments as it is a significant security risk.