sed用法

很久没使用sed命令，今天有一个小需求需要对一批文件的内容进行修改，于是想起sed命令，顺便回顾一下。

文本的内容大致是

item [5]:
		class = "IntervalTier"
		name = "PhonAlign"
		xmin = 0.0
		xmax = 1.799688
		intervals: size = 10
		intervals [1]:
			xmin = 0.0
			xmax = 0.21
			text = "#"
		intervals [2]:
			xmin = 0.21
			xmax = 0.25
			text = "ts"
		intervals [3]:
			xmin = 0.25
			xmax = 0.28
			text = "u"
		intervals [4]:
			xmin = 0.28
			xmax = 0.51
			text = "o"
		intervals [5]:
			xmin = 0.51
			xmax = 0.71
			text = "ts"
		intervals [6]:
			xmin = 0.71
			xmax = 0.74
			text = "u"
		intervals [7]:
			xmin = 0.74
			xmax = 1.02
			text = "o"
		intervals [8]:
			xmin = 1.02
			xmax = 1.23
			text = "ts"
		intervals [9]:
			xmin = 1.23
			xmax = 1.76
			text = "u"
		intervals [10]:
			xmin = 1.76
			xmax = 1.799688
			text = "o"
	item [6]:
		class = "IntervalTier"
		name = "TokensAlign"
		xmin = 0.0
		xmax = 1.799688
		intervals: size = 4
		intervals [1]:
			xmin = 0.0
			xmax = 0.21
			text = "#"
		intervals [2]:
			xmin = 0.21
			xmax = 0.51
			text = "做"
		intervals [3]:
			xmin = 0.51
			xmax = 1.02
			text = "做"
		intervals [4]:
			xmin = 1.02
			xmax = 1.799688
			text = "做"
	item [7]:
		class = "IntervalTier"
		name = "Activity"
		xmin = 0.0
		xmax = 1.799688
		intervals: size = 2
		intervals [1]:
			xmin = 0.0
			xmax = 0.21
			text = "silence"
		intervals [2]:
			xmin = 0.21
			xmax = 1.799688
			text = "speech"

主要替换的位置是'做'这个次替换成对应的拼音

稍微观察一下文件的特点，由于替换的位置位于item[6]~item[7]这两个字符串之间。于是使用

echo "sed -i -E '/item \[6\]/,/item \[7\]/s/text = \"([^#\"]+)\"/text = \"${prex}\"/g'  ${line}"|sh

这里有一个小的知识点，使用sed如果直接用变量格式化，但没办法进行格式化。于是借助echo先将格式化好的字符串输出，然后调用sh命令执行。

另外还有一个用法，当需要在shell中判断某个字符串的包含关系，可以用如下的条件判断

if [[ $line =~ "_" ]]