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Every line in the rules file contains at least one key value pair. There are two kinds of
keys, match and assignment keys. If all match keys match their values, the rule is applied
and the assignment keys are assigned the specified value. A matching rule may specify
the name of the device node, add symlinks pointing to the node, or run a specified
program as part of the event handling. If no matching rule is found, the default device
node name is used to create the device node. The rule syntax and the provided keys to
match or import data are described in the udev man page.
21.7 Persistent Device Naming
The dynamic device directory and the udev rules infrastructure make it possible to
provide stable names for all disk devices—regardless of their order of recognition or
the connection used for the device. Every appropriate block device the kernel creates
is examined by tools with special knowledge about certain buses, drive types, or file
systems. Along with the dynamic kernel-provided device node name, udev maintains
classes of persistent symbolic links pointing to the device:
/dev/disk
|-- by-id
|
|-- scsi-SATA_HTS726060M9AT00_MRH453M4HWHG7B -> ../../sda
|
|-- scsi-SATA_HTS726060M9AT00_MRH453M4HWHG7B-part1 -> ../../sda1
|
|-- scsi-SATA_HTS726060M9AT00_MRH453M4HWHG7B-part6 -> ../../sda6
|
|-- scsi-SATA_HTS726060M9AT00_MRH453M4HWHG7B-part7 -> ../../sda7
|
|-- usb-Generic_STORAGE_DEVICE_02773 -> ../../sdd
|
`-- usb-Generic_STORAGE_DEVICE_02773-part1 -> ../../sdd1
|-- by-label
|
|-- Photos -> ../../sdd1
|
|-- SUSE10 -> ../../sda7
|
`-- devel -> ../../sda6
|-- by-path
|
|-- pci-0000:00:1f.2-scsi-0:0:0:0 -> ../../sda
|
|-- pci-0000:00:1f.2-scsi-0:0:0:0-part1 -> ../../sda1
|
|-- pci-0000:00:1f.2-scsi-0:0:0:0-part6 -> ../../sda6
|
|-- pci-0000:00:1f.2-scsi-0:0:0:0-part7 -> ../../sda7
|
|-- pci-0000:00:1f.2-scsi-1:0:0:0 -> ../../sr0
|
|-- usb-02773:0:0:2 -> ../../sdd
|
|-- usb-02773:0:0:2-part1 -> ../../sdd1
`-- by-uuid
|-- 159a47a4-e6e6-40be-a757-a629991479ae -> ../../sda7
|-- 3e999973-00c9-4917-9442-b7633bd95b9e -> ../../sda6
`-- 4210-8F8C -> ../../sdd1
Dynamic Kernel Device Management with udev
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