Unix file permissions
Every Unix file has a set of permissions that determine if a user can read, write, or execute the file.
Permission flags
┌──────────── Type of file
│ ┌────────── User permissions
│ │ ┌─────── Group permissions
│ │ │ ┌──── Other permissions
│ │ │ │
-rwxr-xr-x 1 user group 7041 Sep 26 18:06 file.txt
| Value | Meaning |
|---|
- | Permission has not been granted. |
r | File is readable. |
w | File is writable. For directories, files may be created or removed. |
x | File is executable. For directories, you can access it and list its files. |
Modifying permissions
chmod can be used to change the permissions of a file.- A common way to set up permissions is to use octal values.
| Octal | Binary | Flags |
|---|
| 0 | 000 | --- |
| 1 | 001 | --x |
| 2 | 010 | -w- |
| 3 | 011 | -wx |
| 4 | 100 | r-- |
| 5 | 101 | r-x |
| 6 | 110 | rw- |
| 7 | 111 | rwx |
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