Problem During the adoption of Mmark for math posts on this blog, I had to insert markup: mmark at the last line of front matter of the source file of each math post.
Seek help I separated this into two SO questions
Sed conditional match and execute command with offset, and A question about AWK multiple line recognition. Solution From #1., I learnt the use of variables in AWK scripts. From #2, some users explained how these variables can be used for multi-line regex search.