Question

I want to join lines between opening tag and closing tag with class named “content_subhd”,
For example:

<span class="content_subhd">1

2

3 </span>

<span class="xyz">1

2

3</span>

Output should be:

<span class="content_subhd">123</span>

<span class="xyz">1

2

3

</span>

How can this be achieve, any suggestion?

Answer 1

awk '/<span class="content_subhd">/, /<\/span>/ {
  r = r ? r $0 : $0
  if (/<\/span>/) {
    print r; r = x
    }
  next
  }1' infile

If you want to replace the content of your existing file:

awk > _new_ '/<span class="content_subhd">/, /<\/span>/ {
  r = r ? r $0 : $0
  if (/<\/span>/) {
    print r; r = x
    }
  next
  }1' your_file && 
    mv -- _new_ your_file 

Added solution for mass replacement (as per OP request):

find <your arguments here> | 
  while IFS= read -r; do
    awk > _new_ '/<span class="content_subhd">/, /<\/span>/ {
  r = r ? r $0 : $0
  if (/<\/span>/) {
    print r; r = x
    }
  next
  }1' "$REPLY" && 
    mv -- _new_ "$REPLY" 
  done