Text Editing

#Unwrap hard-wrapped paragraphs

# shell
awk '{printf "%s ",$0} /^$/{printf "\n\n"} END{print ""}' Script.md

Alternatively if the file is a Markdown file, starting Markdown Composer and copying the text from the browser can also work.

#Replace second match

# shell
sed 's/\.png/.jpeg/2'

#Reverse Lines of File

# shell
tail -r

Processes all lines of the file by default.