[Chapter 22] 22.20 Why Can't You Change File Ownership Under BSD UNIX?
Author: Jerry Peek, Tim O'Reilly & Mike Loukides
Date: 1998-08-04T21:40:42Z

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| Chapter 22 File Security, Ownership, and Sharing |

## 22.20 Why Can't You Change File Ownership Under BSD UNIX?

[Chris is explaining why Berkeley UNIX systems allow only root (1.24) to change a file's ownership. If you need to change ownership, there is a workaround (22.21). - JP]

This restriction is not bogus, because the system supports disk quotas (24.17). If you could give away your own files, you could:

>     mkdir .hide; chmod 700 .hide
>     cd .hide
>     create_huge_file >foo
>     chown prof1 foo
>     create_huge_file >bar
>     chown prof2 bar
>     create_huge_file >baz
>     chown prof3 baz

All you would need do is find someone with a high quota or no quota (such as a professor) who does not often check his own usage (such as a professor) and probably does not care that the disk is 99 percent full (such as a, er, well, never mind), and then give away files as necessary to keep under your own quota. You could regain ownership of the file by copying it to another disk partition, removing the original, and copying it back.

- CT in comp.unix.questions on Usenet, 6 July 1989

22.19 Shell Scripts Must be Readable and (Usually) Executable |  | 22.21 How to Change File Ownership Without chown