using /dev/null in chrooted enviroment

Tzachi Tager tzachi_tager at
Fri Dec 30 09:34:27 PST 2005

sorry to bother again, but is there anybody that has been dealing with issues regarding creating chrooted enviroment in FreeBSD6.0 (i didn't have such problem in previous releases: 5.4, 5.1 etc..)? Some help would be greatly appreciated.

Tzachi Tager <tzachi_tager at> wrote:

Giorgos Keramidas <keramida at> wrote:  On 2005-12-27 06:49, Tzachi Tager wrote:
> Hi,
> I'm trying to create chrooted enviroment, i did the folllowing
> in the chrooted enviroment:
> mknode c null 0 24
> mknode c zero 0 25
> And then i did chroot and those files are under /dev, but when
> i wrote a short program in C that tries to open /dev/null
> (within the chrooted env.) i got:
> "/dev/null-operation is not supported"

> You forgot to mention what version of FreeBSD you are using. It
> may also help to see the contents of the chrooted /dev directory.


We are using:

FreeBSD freebsd6.0 6.0-RELEASE FreeBSD 6.0-RELEASE #0: Thu Nov  3 09:36:13 UTC 2005  root at x64.samsco.home:/usr/obj/usr/src/sys/GENERIC  i386

We tried:

1) To create only /dev/null and /dev/zero (that configuration worked in FreeBSD 5.4)

2) To create the same /dev contents via: tar -cf - /dev | tar -xf -

The original system has /dev mounted as: devfs on /dev (devfs, local)

> Only by doing mount of devfs it seems to work fine, but i
> prefer not to do mount every time (because then i get that my
> chrooted enviroment pathname is too long for FreeBSD)

> A complete trace of the commands you are running and the exact
> error message is probably necessary here.

The very simple C program doesn't run in chroot:

int main() {
    if (open ("/dev/null", O_WRONLY) == -1) {
       perror ("open");

It issues: "open: Operation not supported".

PS: It seems like if we mount devfs to the chrooted env - everything works. The problem is that chroot directory can be placed everywhere, but mount doesn't accept very long path:

# mount -t devfs none dev
mount_devfs: File name too long

# pwd

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