On Sat, Jan 24, 2026 at 16:09:12 +0500, Alexander V. Makartsev wrote: > "cp -r /dev/ /tmp/RFS/dev/" is wrong! Don't do that. > Think about it, "cp" command will copy block devices such as /dev/sda like > files into /tmp/RFS, basically into itself until it runs out of free space.
A reasonable guess, but it's not correct. hobbit:~$ mkdir d1 hobbit:~$ mkfifo d1/pipe hobbit:~$ cp -r d1 d2 hobbit:~$ ls -l d1 d2 d1: total 0 prw-rw-r-- 1 greg greg 0 Jan 24 09:25 pipe| d2: total 0 prw-rw-r-- 1 greg greg 0 Jan 24 09:25 pipe| ============================= hobbit:~$ ls -l /dev/null crw-rw-rw- 1 root root 1, 3 Jan 14 18:21 /dev/null hobbit:~$ sudo mknod d1/null c 1 3 [sudo] password for greg: hobbit:~$ sudo rm -rf d2 hobbit:~$ sudo cp -r d1 d2 hobbit:~$ ls -l d1 d2 d1: total 0 crw-r--r-- 1 root root 1, 3 Jan 24 09:27 null prw-rw-r-- 1 greg greg 0 Jan 24 09:25 pipe| d2: total 0 crw-r--r-- 1 root root 1, 3 Jan 24 09:27 null prw-r--r-- 1 root root 0 Jan 24 09:27 pipe| ============================= Of course, the bind mount solution is better than the cp solution in this case. But the cp solution isn't as wrong as you believed. One would probably want to use -a instead of -r, though, to copy the permissions and ownerships.
