I deleted my /dev/null. How can I restore it?

  • 6
    I once found that /dev/null was replaced with a normal file which only root could write to. I thought for a moment that I would have to reinstall everything but as mentioned below, the recovery is trival if you know the trick. Dec 24 '11 at 12:15
  • 1
    I managed to remove /dev/null by getting my pipe wrong flipping $ and & around when running an rm command in a script. Ouch!
    – flickerfly
    Oct 9 '15 at 22:28
  • @flickerfly You develop scripts as root? Jan 14 '20 at 14:02
  • 2
    If the permissions are required, you have to test it eventually. Didn't say it was in production.
    – flickerfly
    Jan 14 '20 at 15:27
mknod /dev/null c 1 3
chmod 666 /dev/null

Use these command to create /dev/null or use null(4) manpage for further help.

  • 5
    For completeness, I'd note that this applies to all linux-based systems; other systems may have different numbers.
    – Random832
    Dec 21 '11 at 14:53
  • 2
    Also this only sets up the device file itself, it will not restore its permissions. You'll have to chmod go+w it manually.
    – Attila O.
    Jul 3 '15 at 9:44
  • 7
    The number of the beast!
    – wefwefa3
    Nov 6 '15 at 16:21
  • 9
    mknod -m 0666 /dev/null c 1 3 - same thing but shorter
    – fnkr
    Oct 23 '17 at 15:06
  • 1
    mknod -m 0666 /dev/null c 1 3 worked perfectly to restore /dev/null on CentOS 7, just to let other know.
    – Bozzy
    Jan 24 '19 at 10:13

Under many traditional unices, you can recreate devices with their default permissions with the MAKEDEV script. This script is traditionally in /dev but is in /sbin on Ubuntu. Pass it an argument that indicates what devices you want to create; on Ubuntu that's std (you can write MAKEDEV null as well, that creates null as well as a number of other devices).

Under modern Linux systems running udev, you can tell udev to recreate all or some devices based on available drivers and connected hardware, through udevadm trigger:

udevadm trigger --sysname-match=null
  • Is this answer still current? I'm on CentOS 7 and I've just overwritten my /dev/null by mistake, the udevadm trigger --sysname-match=null trick didn't work for me, while mknod -m 0666 /dev/null c 1 3 worked perfectly.
    – Bozzy
    Jan 24 '19 at 10:11
  • @Bozzy I know it worked with the pre-systemd udev. I haven't tried recently, but as far as I know this should still work. If you add --verbose, does it list /sys/devices/virtual/mem/null ? Jan 24 '19 at 22:49
  • Yes, it lists that. I've tried to overwrite again /dev/null on my dev machine, but strangely enough I'm unable to do it here, so I can't do a more in-depth analysis now...
    – Bozzy
    Jan 25 '19 at 10:18

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