About /dev/null (Problem solved)

d00m3d

In a bash shell, if I run:

d00m3d@Xen#ls
.......(list of files)...
d00m3d@Xen#ls > /dev/null
d00m3d@Xen#

So, this is normal.

However, under a chroot environment, e.g.

d00m3d@Xen#mount -t ext3 /dev/hda8 /mnt/hda8
d00m3d@Xen#chroot /mnt/hda8 /bin/sh
sh-3.00#ls > /dev/null
sh: /dev/null: Permission denied
sh-3.00#

Why is that?

How can I use /dev/null under a chroot environment?

7dehao

在chroot后执行
ls -l /dev/null
看看/dev/null的权限是否是crw-rw-rw-

弥敦路九号

-bash-2.05b# ls -l /dev/null
c---------    1 root     root       1,   3  5ÔÂ 30  2004 /dev/null
-bash-2.05b# echo abc > /dev/null
-bash-2.05b#
7dehao兄,我觉得可能没那么简单,我连接的机器上/dev/null 什么权限也没有 c---------
但也是可以把输出重定向到/dev/null

7dehao

Post by 弥敦路九号
-bash-2.05b# ls -l /dev/null
c---------    1 root     root       1,   3  5ÔÂ 30  2004 /dev/null
-bash-2.05b# echo abc > /dev/null
-bash-2.05b#
7dehao兄,我觉得可能没那么简单,我连接的机器上/dev/null 什么权限也没有 c---------
但也是可以把输出重定向到/dev/null

哦，这个我确实没注意到。google了一些发现这个问题还相当普遍，

d00m3d

Post by 7dehao
在chroot后执行
ls -l /dev/null
看看/dev/null的权限是否是crw-rw-rw-

Yes. Still not work :confused:

Post by 7dehao
哦，这个我确实没注意到。google了一些发现这个问题还相当普遍，

Any solutions?

7dehao

网上的解决方案就是我写的那个。兄弟你的那个linux是不是装在Xen虚拟机中的？

d00m3d

Oh, dear!  I misled you, sorry.

Well, I am a great fan of the Half Life first person shooter game.

My desktop computer is named as BlackMesa, which the origin of the game.  Xen is the alien world in Half Life.  I choose this name because I installed Linux in a USB HDD which mean I am working in mobile sense.  There is nothing related to the Xen virtual machine monitor developed by Cambridge U.

Back to my case, I installed Kanotix successfully on a USB HDD, everything is working fine and no problems in booting.  I have installed another source based distro in it but this time I got trouble.  When I chroot into it, I am unable to build the initrd under a chroot environment because of the /dev/null permission problem.

Please help!

7dehao

我怀疑你chroot后是否拥有对/dev目录的写和执行的权限。

d00m3d

That's the problem.

I am root.  Well, of course, normally only root can chroot. /dev/null权限是crw-rw-rw- but I still receive "permission denied" error!  What's happening??? :confused:

minus273

and 'whoami' after chroot...