| |
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| | |
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| | Original ``Unix`` derivatives had a static tree of devices the system |
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| | could support. This was encoded in the ``/dev`` file tree hierarchy. |
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| | This was pretty inflexible in the face of devices being added- and |
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| | removed- from the system as it ran. For this reason, modern device |
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| | removed from the system as it ran. For this reason, modern device |
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| | handling in ``Linux`` and most other ``Unix`` derivatives is |
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| | *dynamic* - the content of ``/dev`` changes to reflect the actual |
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| | state of the system as things get connected or disconnected. (Exactly |
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| | how this is done is outside the purpose of this document, but if you |
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| | care, investigate the ``Linux /sys`` filesystem works.) |
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| | care, investigate how the ``Linux /sys`` filesystem works.) |
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| | |
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| | |
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| | Our Example Problem |
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| | =================== |
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| | |
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| | While the example below is "cooked", it is very much rooted in real |
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| | world ``udev`` application. We want to do the following things: |
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| | world ``udev`` applications. We want to do the following things: |
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| | |
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| | - Make sure that a particular disk always shows up under the same |
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| | name under ``/dev`` no matter how many disks have been connected |
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| | before it. We do that by uniquely identifying a disk and then |
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| | creating a symbolic link to it that never changes. |
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| | - Identify a specific disk no matter what name it was assigned |
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| | name under ``/dev``. |
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| | |
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| | - Create a symbolic link to that disk so that - no matter |
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| | what it's name under ``/dev/`` might be at the moment - |
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| | the symbolic link is always the same. |
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| | |
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| | - Change the user and group ownership of that disk to something |
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| | other than the default of ``root:disk``. |
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| | other than the default (``root:disk``). |
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| | |
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| | - Create a corresponding "raw" character device under ``/dev/raw``. |
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| | This is something you commonly see on database servers and |
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| | it's suffiently useful that's it's worth mentioning here. |
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| | - Create a corresponding "raw" character device under ``/dev/raw`` |
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| | associated with our disk above. This is something commonly |
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| | seen on database servers and it's suffiently useful that's it's |
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| | worth mentioning here. |
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| | |
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| | |
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| | Where Do ``udev`` Rules Live? |
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| | ============================= |
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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 1.102 2013/10/31 21:45:08 tundra Exp $`` |
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| | ``$Id: Deconstructing_Linux_udev_Rules.rst,v 1.103 2013/10/31 21:50:07 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