參考:http://wiki.jikexueyuan.com/project/shell-learning/command-substitution.htmlhtml
命令替換是指 shell 能夠先執行命令,將輸出結果暫時保存,在適當的地方輸出.shell
格式:`command` spa
即用反引號(esc下面那個鍵)將命令括起來,好比htm
DATE=`date`it
echo "date is $DATE"io
輸出結果:date is Mon Aug 7 15:25:05 CST 2017date