$ ( dd if=/dev/zero count=100; dd if=/dev/urandom count=100; dd if=/dev/zero count=100 ) > unsparse
$ cp --sparse=always unsparse sparse $ ls -ls * 52 -rw-r--r--. 1 root root 153600 Apr 14 22:55 sparse 152 -rw-r--r--. 1 root root 153600 Apr 14 22:54 unsparse Great, the file was sparse-ified. On tmpfs. ## now on XFS with reflink support $ cp --debug --sparse=always unsparse sparse 'unsparse' -> 'sparse' copy offload: unknown, reflink: yes, sparse detection: unknown $ ls -ls * 152 -rw-r--r--. 1 root root 153600 Apr 14 22:58 sparse 152 -rw-r--r--. 1 root root 153600 Apr 14 22:54 unsparse The implicit --reflink=auto has won out over the explicit --sparse=always, but at some point prior to coreutils 7.5, --sparse=always would have worked. NEWS for 9.4 included 'cp --sparse=never' will avoid copy-on-write (reflinking) and copy offloading, to ensure no holes present in the destination copy. [bug introduced in coreutils-9.0] but we lack the opposite. I couldn't spot the discussion, if any, around the patch https://lists.gnu.org/archive/html/coreutils/2023-08/msg00052.html I'm using coreutils 9.5 on Fedora 41. Cheers, Phil
