增加 Udevadm 说明.

Signed-off-by: chen.yang <chen.yang@yuzhen-iot.com>

Software/Applications/Udevadm/Udevadm_说明.md

@@ -0,0 +1,62 @@
+# Udevadm 说明
+
+## 1. 安装
+
+```bash
+# Ubuntu 16.04
+apt install udev
+```
+
+## 2. 使用
+
+### 2.1. 监控 UEvent
+
+```bash
+udevadm monitor
+
+# 热插拔设备出现类似 Log
+KERNEL[4907.940589] add      /devices/platform/soc/2100000.aips-bus/2184200.usb/ci_hdrc.1/usb2/2-1/2-1:1.9/ttyUSB7/tty/ttyUSB7 (tty)
+UDEV  [4908.211629] add      /devices/platform/soc/2100000.aips-bus/2184200.usb/ci_hdrc.1/usb2/2-1/2-1:1.9/ttyUSB7/tty/ttyUSB7 (tty)
+```
+
+### 2.2. 获取 UDev 信息
+
+```bash
+udevadm info <device node>
+# 如
+udevadm info /dev/ttyUSB7
+
+P: /devices/platform/soc/2100000.aips-bus/2184200.usb/ci_hdrc.1/usb2/2-1/2-1:1.9/ttyUSB7/tty/ttyUSB7
+N: ttyUSB7
+S: serial/by-id/usb-LONGSUNG_M5700-if09-port0
+S: serial/by-path/platform-ci_hdrc.1-usb-0:1:1.9-port0
+E: DEVLINKS=/dev/serial/by-id/usb-LONGSUNG_M5700-if09-port0 /dev/serial/by-path/platform-ci_hdrc.1-usb-0:1:1.9-port0
+E: DEVNAME=/dev/ttyUSB7
+E: DEVPATH=/devices/platform/soc/2100000.aips-bus/2184200.usb/ci_hdrc.1/usb2/2-1/2-1:1.9/ttyUSB7/tty/ttyUSB7
+E: ID_BUS=usb
+E: ID_MODEL=M5700
+E: ID_MODEL_ENC=M5700
+E: ID_MODEL_ID=4d11
+E: ID_PATH=platform-ci_hdrc.1-usb-0:1:1.9
+E: ID_PATH_TAG=platform-ci_hdrc_1-usb-0_1_1_9
+E: ID_REVISION=0000
+E: ID_SERIAL=LONGSUNG_M5700
+E: ID_TYPE=generic
+E: ID_USB_DRIVER=option
+E: ID_USB_INTERFACES=:020600:0a0000:ff0000:
+E: ID_USB_INTERFACE_NUM=09
+E: ID_VENDOR=LONGSUNG
+E: ID_VENDOR_ENC=LONGSUNG
+E: ID_VENDOR_FROM_DATABASE=Spreadtrum Communications Inc.
+E: ID_VENDOR_ID=1782
+E: MAJOR=188
+E: MINOR=7
+E: SUBSYSTEM=tty
+E: TAGS=:systemd:
+E: USEC_INITIALIZED=4908169711
+```
+
+## 外部参考资料
+
+1. [How to Use Udev for Device Detection and Management in Linux](https://www.tecmint.com/udev-for-device-detection-management-in-linux/)
+2. [udevadm 命令详解](https://www.cnblogs.com/carriezhangyan/p/9564900.html)