Today at work a client had
rm -rf /dev and ended up deleting two files in
/dev/shm that forced his site to no longer work.
From what I learned previously
/dev is not virtual, but a fellow technician had suggested to reboot the server because
/dev is virtual like
/proc. Sure enough I rebooted the server and the files that the client rm -rf’d were there.
So, my question is; is
/dev virtual? Is it the kind of virtual like
/proc? Is there more documentation on this? How can I restore the
/dev files without a server reboot?
The answer for a very long time has been “sort of”.
Currently the Linux device tree is managed by
udev, a userspace device manager which replaced devfs several years ago. udev populates /dev with any device nodes the system needs, depending on the rules configured in its configuration files.
On the newest Linux systems, /dev is in a temporary RAM disk provided by
devtmpfs. You could call these virtual.
devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=6109940k,nr_inodes=1527485,mode=755)
The only reason for actual device nodes in /dev nowadays is for the boot environment, before udev has started. Typically only
/dev/null are needed in the actual filesystem, which is sufficient to get to the point where udev can be started. It will then provide everything else.
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