chmod

        # File.chmod

(from ruby core)
---
    File.chmod(mode_int, file_name, ... )  ->  integer

---

Changes permission bits on the named file(s) to the bit pattern
represented by *mode_int*. Actual effects are operating system dependent
(see the beginning of this section). On Unix systems, see `chmod(2)` for
details. Returns the number of files processed.

    File.chmod(0644, "testfile", "out")   #=> 2


(from ruby core)
---
    file.chmod(mode_int)   -> 0

---

Changes permission bits on *file* to the bit pattern represented by
*mode_int*. Actual effects are platform dependent; on Unix systems, see
`chmod(2)` for details. Follows symbolic links. Also see File#lchmod.

    f = File.new("out", "w");
    f.chmod(0644)   #=> 0