I was thinking about: Is the sh operator >> to redirect and append a single fwrite to stdout atomic or not?
Can you prove your answer to the question above? And on cmd.exe, is the operator >> atomic? Then I thought about the following POS. It is a command for sh: while [[ true ]] ; do cat a | cat /dev/stdin >> a ; done ; If the file a contains any byte it will fill your disk. If the file a is empty it will consume your CPU time. It does not use dd.
