Linux service: haldaemon service overview

There was a problem these days, the USB mouse and keyboard are not available. The final investigation found that the haldaemon service was shut down. The biggest feature of Fedra Core is the ability to automatically mount storage devices such as USB flash drives or mobile hard drives. Hotplug, udev, messagebus, haldaemon, gaimn are essential when implementing the automount feature. Among them, hotplug is the core. When the hardware device is connected to the system, the hotplug service first detects and automatically configures the kernel state, and calls to add the relevant kernel module. Udev is responsible for dynamically maintaining the /dev directory, keeping the /dev directory consistent with the current system state, and creating device documentation such as /dev/sdax. The messagebus service is responsible for passing messages between various system processes. Haldaemon accepts the message sent by udev through D-BUS and then adjusts the fstab-sync to modify the fstab file to dynamically create a subdirectory under the /media directory as the mount point. After gamin detects a change in fstab, it is responsible for notifying the desktop system. The desktop system creates a drive icon in the “Computer
” project. Therefore, when implementing automatic loading of the mobile storage device, it must be ensured that several of the above services are started normally. The haldaemon service may be inadvertently shut down during system optimization, which can result in the inability to dynamically change the /etc/fstab file, which prevents the mobile device from being automatically recognized when it is connected to the system. At this point, you can manually mount it by the mount command. In addition, if the HAL service startup fails to display when the system starts, it is likely that the messagebus service has not started. Then restart the messagebus service and restart haldaemon