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jirislav
Asked: 2017-11-09 00:02:06 +0800 CST

Does new block device always appear in the /dev directory?

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I'm wondering, if it is possible for a new block device (e.g. SCSI/USB data disk device) connected, to show up somewhere else, than in the /dev directory?

Btw, let's not consider symlinks appearing in /dev/disk nor /dev/block.

NOTE: I've already read an answer to What does /dev/sda for linux mean, but I'm still unsure about my question.

udev

1 Answers

  1. Best Answer

    In recent systems, a special virtual filesystem (devtmpfs) is mounted on /dev:

    $ findmnt /dev
TARGET SOURCE FSTYPE   OPTIONS
/dev   udev   devtmpfs rw,nosuid,relatime,size=1000388k,nr_inodes=250097,mode=755

    You can mount devtmpfs elsewhere and whatever's in /dev will appear there too:

    $ sudo mount -t devtmpfs udev /mnt
$ ls /mnt/sda*
/mnt/sda  /mnt/sda1  /mnt/sda2  /mnt/sda5

    Alternately, you could use udev to populate another directory in addition to /dev.

    Aside from such tricks, nope. The devtmpfs filesystem is automatically populated by the kernel. Wherever that filesystem is mounted, the devices will show up there.

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