目的：每天 17:25 用 notify-send 弹出提醒。

系统：deepin 15.8

>>>> $ crontab -e
# 分钟 小时 日期 月份 周几 用户名 要执行的命令
  08   12   *    *    *           export DISPLAY=:0.0; notify-send  -i  application-exit         "提醒"  "测试测试...."
  25   17   *    *    *           export DISPLAY=:0.0; notify-send  -i  application-exit         "提醒"  "该写日志了...."

>>>> $ systemctl status cron
● cron.service - Regular background program processing daemon
   Loaded: loaded (/lib/systemd/system/cron.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2018-12-05 08:20:30 CST; 4h 15min ago
     Docs: man:cron(8)
Main PID: 4489 (cron)
    Tasks: 3 (limit: 4915)
   Memory: 4.3M
   CGroup: /system.slice/cron.service
           ├─ 4489 /usr/sbin/cron -f
           ├─25830 dbus-launch --autolaunch=0c5af4c7bfe142559558f83d19899b34 --binary-syntax --close-stderr
           └─25833 /usr/bin/dbus-daemon --syslog-only --fork --print-pid 5 --print-address 7 --session

12月 05 12:08:02 user dbus-daemon[25833]: [session uid=1000 pid=25829] Failed to activate service 'org.freedesktop.Notifications': timed out (service_start_timeout=120000ms)
12月 05 12:08:02 user dbus-daemon[25833]: [session uid=1000 pid=25829] Activating service name='org.freedesktop.Notifications' requested by ':1.3' (uid=1000 pid=25916 comm="notify-send -i application-exit ???1??? ??????????" label="unconfined")
12月 05 12:08:02 user org.freedesktop.Notifications[25833]: I only run the Deepin Desktop!
12月 05 12:10:02 user dbus-daemon[25833]: [session uid=1000 pid=25829] Failed to activate service 'org.freedesktop.Notifications': timed out (service_start_timeout=120000ms)
12月 05 12:14:01 user dbus-daemon[25833]: [session uid=1000 pid=25829] Activating service name='org.freedesktop.Notifications' requested by ':1.4' (uid=1000 pid=26406 comm="notify-send -i application-exit ???1??? ??????????" label="unconfined")
12月 05 12:14:01 user org.freedesktop.Notifications[25833]: I only run the Deepin Desktop!
12月 05 12:16:01 user dbus-daemon[25833]: [session uid=1000 pid=25829] Failed to activate service 'org.freedesktop.Notifications': timed out (service_start_timeout=120000ms)
12月 05 12:20:01 user dbus-daemon[25833]: [session uid=1000 pid=25829] Activating service name='org.freedesktop.Notifications' requested by ':1.6' (uid=1000 pid=26798 comm="notify-send -i application-exit ???1??? ??????????" label="unconfined")
12月 05 12:20:01 user org.freedesktop.Notifications[25833]: I only run the Deepin Desktop!
12月 05 12:22:01 user dbus-daemon[25833]: [session uid=1000 pid=25829] Failed to activate service 'org.freedesktop.Notifications': timed out (service_start_timeout=120000ms)




notify-send 的用法：
$ notify-send  -i  "图标"  "标题"  "消息正文"


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