Linux Shell中的命令替换

Posted 2020-11-30 99876w

Shell脚本中最有用的特性之1就是可以从命令输出中提取信息，并将其赋给变量。有两种方法可以将命令输出赋值给变量。

• 反引号字符(`)

反引号字符位于键盘上ESC键的下面。赋值给变量的情势以下：

test=`date`

# demo
$ test=`date`
$ echo $test
2017年 1月11日 星期3 21时26分04秒 CST

两个反引号字符之间是shell命令，shell命令的履行结果赋值给test，注意=两边不能有空格。

• $()情势

赋值给变量的情势以下：

test=$(date)

# demo
$ test=$(date)
$ echo $test
2017年 1月11日 星期3 21时26分35秒 CST

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