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DeviceSpec

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Alexey Gladkov edited this page Sep 12, 2022 · 1 revision

Device specification

A device can be specified in several ways:

  • /<filename> - The usual way to specify a device is to specify the device filename. You can specify the full path to the device file on which the root of the filesystem is located.

  • LABEL=<label> - If the file system has a label, then you can define it through it. The value should begin with the LABEL= prefix. In this case, the <label> must be unique among block devices. Otherwise, a device that is initialized first will be used.

  • UUID=<uuid> - For block devices with a filesystem, you can specify the UUID as the device identifier. The value should begin with the UUID= prefix.

  • PARTUUID=<uuid> - The UUID may be either an EFI/GPT UUID, or refer to an MSDOS partition.

  • PARTLABEL=<label> - The <label> being the GPT partition label. MSDOS partitions do not support labels!

  • SERIAL=<serial> - The <serial> has the format: <ID_MODEL>_<ID_SERIAL_SHORT> It's possible to get these values using the /lib/udev/ata_id.

  • <major:<minor> - you can specify device major and minor.

  • <HEX-number> - major is (number / 256), minor is (number % 256).

  • /dev/disk/by-uuid/<UUID_ENC>, /dev/disk/by-label/<LABEL_ENC>, /dev/block/<major>:<minor>, /dev/disk/by-partuuid/<PARTUUID>, /dev/disk/by-partlabel/<PARTLABEL> - There is also an alternative form for specifying the above methods.

If the specified value is not unique within the system, the result will not be predictable.

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