解决crontab定时执行notify-send无法弹窗（ubuntu18.04）

定时提示休息脚本

ubuntu没有好用的定时提醒休息的软件，workrave，safeeyes都试过，计时总是会被重置，无法按时提醒。有网友分享利用notify-send和crontab，gnome-screensaver实现简单的提醒锁屏。

问题描述

在crontab下执行notify-send无法弹出窗口

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原因分析：

没有设置XDG_RUNTIME_DIR

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解决方案：

网上有很多方法，比如：

1. notify-send的执行路径为绝对路径（无效）

which nofity-send
* * * * * /usr/bin/notify-send -u normal -t 500 -i appointment-new '1分钟后锁屏' '注意休息，善待眼睛'

2. 配置DISPLAY（无效）

* * * * * export DISPLAY=:0.0;notify-send -u normal -t 500 -i appointment-new '1分钟后锁屏' '注意休息，善待眼睛'

3. 最后借鉴了一个网友的分享，需要配置XDG_RUNTIME_DIR，成功解决：

* * * * * XDG_RUNTIME_DIR=/run/user/$(id -u) /usr/bin/notify-send -u normal -t 500 -i appointment-new '1分钟后锁屏' '注意休息，善待眼睛'

完整的crontab配置：

 c/crontab                                                                                                                                                                                    buffers 
  1 #DISPLAY=:0                                                                                                                                                                                           
  2 # Edit this file to introduce tasks to be run by cron.                                                                                                                                                
  3 #                                                                                                                                                                                                     
  4 # Each task to run has to be defined through a single line                                                                                                                                            
  5 # indicating with different fields when the task will be run                                                                                                                                          
  6 # and what command to run for the task                                                                                                                                                                
  7 #                                                                                                                                                                                                     
  8 # To define the time you can provide concrete values for                                                                                                                                              
  9 # minute (m), hour (h), day of month (dom), month (mon),                                                                                                                                              
 10 # and day of week (dow) or use '*' in these fields (for 'any').#                                                                                                                                      
 11 # Notice that tasks will be started based on the cron's system                                                                                                                                        
 12 # daemon's notion of time and timezones.                                                                                                                                                              
 13 #                                                                                                                                                                                                     
 14 # Output of the crontab jobs (including errors) is sent through                                                                                                                                       
 15 # email to the user the crontab file belongs to (unless redirected).                                                                                                                                  
 16 #                                                                                                                                                                                                     
 17 # For example, you can run a backup of all your user accounts                                                                                                                                         
 18 # at 5 a.m every week with:                                                                                                                                                                           
 19 # 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/                                                                                                                                                     
 20 #                                                                                                                                                                                                     
 21 # For more information see the manual pages of crontab(5) and cron(8)                                                                                                                                 
 22 #                                                                                                                                                                                                     
 23 # m h  dom mon dow   command                                                                                                                                                                          
 24                                                                                                                                                                                                       
 25                                                                                                                                                                                                       
 26 58 * * * * XDG_RUNTIME_DIR=/run/user/$(id -u) /usr/bin/notify-send -u normal -t 500 -i appointment-new '1分钟后锁屏' '注意休息，善待眼睛'                                                             
 27 59 * * * * export DISPLAY=:0.0;XDG_RUNTIME_DIR=/run/user/$(id -u) gnome-screensaver-command -l           

参考：https://blog.youkuaiyun.com/shjinyuan/article/details/106265238