SED正则表达式中[方括号]的特殊处理

今天被这个方括号懵晕了，特此记录

例如： 去除输入字符串“1[2.3]4[ab,c]”中的所有方括号和逗号：

$ echo "1[2.3]4[ab,c]"|sed -e "s/[,\]\[]//g"
1[2.3]4[ab,c]
 

It doesn't work!

原因：Regular Expressions

The ( ']' ) shall lose its special meaning and represent itself in a bracket expression if it occurs first in the list (after an initial ( '^' ), if any).

解决方案：关键是要把 ] 右方括号不加escape放在首位.

$ echo "1[2.3]4[ab,c]"|sed -e "s/[][,]//g"
12.34abc

$ echo "1[2.3]4[ab,c]"|sed -e "s/[]\[,]//g"
12.34abc

$ echo "1[2.3]4[ab,c]"|sed -e "s/[],[]//g"
12.34abc
 

The order of some characters is important:

• - should be at the end like this -]
• [] should be like that [][other characters]
• ' should be escaped like that '\''
• not begin with ^ like in [^
• not begin with [. [= [: and end with .] =] :]
• not end with $]

References:

regex - How to escape square closing bracket in sed - Stack Overflow

Regular Expressions