udev是在用户空间运行的守护进程,它会监听内核的uevent事件,根据事件和配置的udev规则,添加或者删除设备文件。
udev规则在/etc/udev/rules.d目录中,所有的规则文件必须以”.rules”为后缀名。
通过udevadm可以读取设备信息,例如:
$udevadm info /dev/sda
P: /devices/pci0000:00/0000:00:01.1/ata1/host0/target0:0:0/0:0:0:0/block/sda
N: sda
S: disk/by-id/ata-VBOX_HARDDISK_VB0e44d14f-0256c867
S: disk/by-path/pci-0000:00:01.1-ata-1.0
E: DEVLINKS=/dev/disk/by-id/ata-VBOX_HARDDISK_VB0e44d14f-0256c867 /dev/disk/by-path/pci-0000:00:01.1-ata-1.0
E: DEVNAME=/dev/sda
E: DEVPATH=/devices/pci0000:00/0000:00:01.1/ata1/host0/target0:0:0/0:0:0:0/block/sda
E: DEVTYPE=disk
E: ID_ATA=1
E: ID_ATA_FEATURE_SET_PM=1
E: ID_ATA_FEATURE_SET_PM_ENABLED=1
E: ID_ATA_WRITE_CACHE=1
E: ID_ATA_WRITE_CACHE_ENABLED=1
E: ID_BUS=ata
E: ID_MODEL=VBOX_HARDDISK
E: ID_MODEL_ENC=VBOX\x20HARDDISK\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20
E: ID_PART_TABLE_TYPE=dos
E: ID_PATH=pci-0000:00:01.1-ata-1.0
E: ID_PATH_TAG=pci-0000_00_01_1-ata-1_0
E: ID_REVISION=1.0
E: ID_SERIAL=VBOX_HARDDISK_VB0e44d14f-0256c867
E: ID_SERIAL_SHORT=VB0e44d14f-0256c867
E: ID_TYPE=disk
E: MAJOR=8
E: MINOR=0
E: SUBSYSTEM=block
E: TAGS=:systemd:
E: USEC_INITIALIZED=27143