udev cdrom 规则无法运行脚本

【问题标题】：udev cdrom rules failing to run scriptsudev cdrom 规则无法运行脚本
【发布时间】：2017-05-29 21:16:56
【问题描述】：

以下是我在 /etc/udev/rules.d/10-autodvd.rules 中的规则文件

SUBSYSTEM=="block", KERNEL=="sr0", ENV{ID_CDROM_MEDIA_DVD}=="1", ACTION=="change", RUN+="/usr/local/bin/makemkv.sh sr0"
SUBSYSTEM=="block", KERNEL=="sr1", ENV{ID_CDROM_MEDIA_DVD}=="1", ACTION=="change", RUN+="/usr/local/bin/makemkv.sh sr1"
SUBSYSTEM=="block", KERNEL=="sr2", ENV{ID_CDROM_MEDIA_DVD}=="1", ACTION=="change", RUN+="/usr/local/bin/makemkv.sh sr2"
SUBSYSTEM=="block", KERNEL=="sr3", ENV{ID_CDROM_MEDIA_DVD}=="1", ACTION=="change", RUN+="/usr/local/bin/makemkv.sh sr3"
SUBSYSTEM=="block", KERNEL=="sr4", ENV{ID_CDROM_MEDIA_DVD}=="1", ACTION=="change", RUN+="/usr/local/bin/makemkv.sh sr4"

在实际运行脚本时似乎真的会受到影响，有没有更好的方法来做到这一点？

【问题讨论】：

标签： udev

【解决方案1】：

Udev 按词法对规则文件进行排序，在应用您的规则时，ID_CDROM_MEDIA_DVD 变量可能尚未设置。这是默认安装 systemd udev 的情况。 ID_CDROM* 变量在 60-cdrom_id.rules 中设置，因此您应该重命名规则文件以在此之后排序。

请注意，您不应使用 RUN+= 键启动长时间运行的程序。

   RUN{type}
   [...]
       This can only be used for very short-running
       foreground tasks. Running an event process for
       a long period of time may block all further
       events for this or a dependent device.

       Starting daemons or other long-running
       processes is not appropriate for udev; the
       forked processes, detached or not, will be
       unconditionally killed after the event handling
       has finished.

你的规则可以写成一条规则：

SUBSYSTEM=="block", KERNEL=="sr[0-4]", ENV{ID_CDROM_MEDIA_DVD}=="1", ACTION=="change", RUN+="/usr/local/bin/makemkv.sh %k"

【讨论】：