如何获取括号中指定的内容？

Question

I want to extract the content written in a file. Let us take an example

{{{
      How 
      R 
      U
}}}

{{{ Hi }}}

I want to print the output like this

 How
 R
 U

 Hi

Answer 1

Well, this is not regex this is using gawk multi-character RS .

awk -v RS='}}}|{{{' 'NF' inputfile

      How
      R
      U

 Hi

You can pipe above command with something like this sed -r 's/^ +//g' to remove extra spaces at the start of the line.

Answer 2

By using regular expressions this becomes tricky, mainly because grep or awk seem not to support the lookahead .

To extract or match only the text within the curly braces this regex could be used: https://regex101.com/r/ASFIFa/1

[^{\}]+(?=})

Therefore you could give a try to the ag - The Silver Searcher , something like this produce your required output:

$ ag -o '[^{\}]+(?=})' input.txt 

To remove the leading spaces:

$ ag -o '[^{\}]+(?=})' input.txt | sed 's/^ *//'

Answer 3

With sed

sed '/{{{/!d;:A;/\}\}\}/!{N;bA};s/{{{//;s/}}}//;s/ *//g' infile

Or

sed -E '/\{{3}/!d;:A;/\}{3}/!{N;bA};s/\{{3}| *|\}{3}//g' infile