Bug 627812

Summary:	sys-apps/coreutils mv behavior with hard links to same file
Product:	Gentoo Linux	Reporter:	Xuefer <xuefer>
Component:	Current packages	Assignee:	Gentoo's Team for Core System packages <base-system>
Status:	RESOLVED INVALID
Severity:	normal	CC:	floppym
Priority:	Normal
Version:	unspecified
Hardware:	All
OS:	Linux
Whiteboard:
Package list:		Runtime testing required:	---

Description Xuefer 2017-08-14 04:14:38 UTC

$ rm -f a b
$ touch a
$ ln a b
$ mv a b
mv: 'a' and 'b' are the same file

expected: mv is expected to overwrite b using a, which mean in this case, unlink a, rename a to b

Comment 1 Mike Gilbert gentoo-dev

2017-08-14 04:44:07 UTC

POSIX says this behavior is correct.

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/mv.html

"The specification ensures that mv a a will not alter the contents of file a, and allows the implementation to issue an error that a file cannot be moved onto itself. Likewise, when a and b are hard links to the same file, mv a b will not alter b, but if a diagnostic is not issued, then it is unspecified whether a is left untouched (as it would be by the rename() function) or unlinked (reducing the link count of b)."