| |
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| | ``udev`` is one of those pieces of ``Linux`` that is fairly well |
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| | documented and not very well understood. This note isn't intended as |
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| | a general introduction to writing ``udev`` rules, but, rather, a brief |
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| | introduction to the topic by way of specific example. |
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| | |
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| | .. NOTE:: The examples and descriptions below assume you |
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| | are running as ``root``. Most of the commands |
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| | described will either return nothing or will not |
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| | work at all unless you are ``root``. |
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| | |
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| | |
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| | Why Bother With ``udev``? |
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| | ========================= |
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| |
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| | - ``KERNEL=="sd*"`` |
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| | - ``PROGRAM=="/sbin/scsi_id --whitelisted /dev/$name"`` |
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| | - ``RESULT=="1ATA_VBOX_HARDDISK_VB5f712327-2bb4be0c"`` |
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| | - ``SYMLINK+="my_fine-disk01"`` |
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| | - ``OWNER:="3009"`` |
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| | - ``GROUP:="421"`` |
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| | - ``MODE:="0600",`` |
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| | - ``"OWNER:="3009", GROUP:="421", MODE:="0600",`` |
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| | - ``RUN=="/bin/raw /dev/raw/raw1 /dev/$name"`` |
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| | |
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| | Now, let's look at the second rule: |
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| | |
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| | - ``KERNEL=="raw1"`` |
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| | - ``SYMLINK+="rmy_fine-disk01"`` |
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| | - ``OWNER:="3009"`` |
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| | - ``GROUP:="421"`` |
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| | - ``MODE:="0600"`` |
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| | - ``"OWNER:="3009", GROUP:="421", MODE:="0600"`` |
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| | |
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| | |
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| | |
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| | Other Thoughts |
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| | |
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| | Final Thoughts |
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| | ============== |
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| | |
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| | Obviously, you'd have to have another pair of rules for each additional |
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| | disk you want to manage this way. Adding another disk would be a matter |
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| | of using ``scsi_id`` to get its ``wwid`` and for the ``RESULT`` field |
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| | of the first rule. You'd also have to change references to ``my_fine_disk01`` |
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| | and ``raw1``. |
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| | Obviously, you'd have to have another pair of rules for each |
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| | additional disk you want to manage this way. Adding another disk |
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| | would be a matter of using ``scsi_id`` to get its ``wwid`` for the |
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| | ``RESULT`` field of the first rule. You'd also have to change any |
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| | references to ``my_fine_disk01`` and ``raw1``. |
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| | |
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| | For reasons that are not entirely clear (to me anyway), the ``raw`` |
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| | command only knows how to create raw devices whose names begin with |
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| | ``raw``, go figure. |
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| | |
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| | Another way to get a unique ID for a device is to tail your system log |
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| | (``tail -f /var/log/messages`` or ``tail -f /var/log/syslog``) and |
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| | watch what happens when you plug your device into, say, a USB port. |
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| | |
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| | If you want to know all the attributes ``udev`` knows about a particular |
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| | device, use this, substituting your device for ``/dev/sdd`` :: |
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| | |
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| | udevadm info --query=all --name /dev/sdd 2>&1| less |
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| | |
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| | The output of this command can be helful in figuring out just which |
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| | attributes and values you need to get to a running rule. |
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| | |
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| | Finally, you can test your rules to see what is matching, again |
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| | substituting for ``/block/sdd``:: |
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| | |
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| | udevadm test /block/sdd 2>&1| less |
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| | |
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| | |
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| | Author |
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| | ====== |
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| | |
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| | Tim Daneliuk - tundra@tundraware.com |
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| | |
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| | Comments and/or improvements welcome! |
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| | Comments, corrections, clarifications, and/or improvements welcome! |
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| | |
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| | |
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| | Document Revision Information |
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| | ============================= |
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| | |
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| | ``$Id: Deconstructing_Linux_udev_Rules.rst,v 1.106 2013/10/31 22:44:17 tundra Exp $`` |
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| | ``$Id: Deconstructing_Linux_udev_Rules.rst,v 1.107 2013/10/31 23:11:30 tundra Exp $`` |
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| | |
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| | You can find the latest version of this document at: |
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| | |
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| | http://www.tundraware.com/TechnicalNotes/Deconstructing-Linux-udev-Rules |
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| | |
tundra
authored
on 31 Oct 2013