chmod Calculator
Unix file permissions in octal and rwx, both ways.
About this tool
Tick read, write and execute for owner, group and others to get the octal mode and the chmod command, or type a mode like 755 or rwxr-xr-x to see what it allows. Includes setuid, setgid and the sticky bit.
How to use it
- Type a mode like 755, 0644 or rwxr-xr-x, or paste the first column of ls -l.
- Or tick read, write and execute for the owner, the group and everyone else.
- Add setuid, setgid or the sticky bit if you need them.
- Enter the file name and copy the chmod command.
Questions
- What does chmod 755 mean?
- The owner can read, write and execute; the group and everyone else can read and execute. It is the usual mode for scripts, programs and folders.
- What is the difference between 644 and 755?
- 644 (rw-r--r--) is for normal files: only the owner can change them and nobody can run them. 755 adds execute permission, which programs need to run and folders need so people can open them.
- Why does my SSH key need 600?
- SSH refuses private keys that other users can read. 600 means only you can read and write the file, which is exactly what it checks for.
- Is chmod 777 ever a good idea?
- Rarely. It lets every user on the machine change or replace the file. When something only works with 777, the real fix is usually the right owner (chown) or group, not wider permissions.
- What do the s and t letters mean?
- s in the owner or group position is setuid or setgid: the program runs with the file owner’s or group’s rights, or new files in a folder inherit its group. t is the sticky bit: in a shared folder like /tmp, people can only delete their own files.
Something not working, or a result looks wrong? Report a problem with this tool