https://www.cnblogs.com/azureology/p/14051040.html
## 背景
希望每次ssh登录树莓派时欢迎信息可以显示系统状态
包括CPU温度与用量，内存和硬盘用量

## 代码
控制树莓派登录欢迎信息的文件有两处

位于`/etc/update-motd.d/`目录下的shell脚本
上述脚本执行完毕后打印`/etc/motd`文本
新建欢迎脚本
```
$ sudo vi /etc/update-motd.d/11-info
```
部分源自Adafruit的开源项目修改而来（已停止维护）
```
#!/bin/sh
uptime | awk '{‌‌‌printf("\nCPU Load: %.2f\t", $(NF-2))}'
free -m | awk 'NR==2{‌‌‌printf("Mem: %s/%sMB %.2f%%\n", $3,$2,$3*100/$2)}'
cat /sys/class/thermal/thermal_zone0/temp|awk '{‌‌‌printf("CPU Temp: %.2f\t",$1/1000)}'
df -h | awk '$NF=="/"{‌‌‌printf "Disk: %.1f/%.1fGB %s\n\n", $3,$2,$5}'
```
添加执行权限
```
$ sudo chmod +x /etc/update-motd.d/11-info
```
取消原始静态欢迎信息（可选）
```
$ sudo mv /etc/motd /etc/motd.sample
```
## 效果
更换前
```
Linux rpi0w 4.19.57+ #1244 Thu Jul 4 18:42:50 BST 2019 armv6l

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Thu Nov 26 19:57:02 2020 from 127.0.0.1
```
更换后
```
Linux rpi0w 4.19.57+ #1244 Thu Jul 4 18:42:50 BST 2019 armv6l
CPU Load: 0.01 Mem: 74/432MB 17.13%
CPU Temp: 29.86 Disk: 2.0/7.1GB 30%
Last login: Thu Nov 26 19:57:02 2020 from 127.0.0.1
```
**********
[Linux的/etc/issue、/etc/issue.net和/etc/motd的区别](https://www.cnblogs.com/pluse/p/5531523.html)