Remove all empty lines in a file

How to Remove all empty lines in a file on Linux and Windows?

Remove empty lines from file.txt via Linux command line

• Option 1: sed -i '/^$/d' file.txt
• Option 2: awk 'NF > 0' file.txt > output.txt
• Option 3: perl -i.backup -n -e "print if /\S/" file.txt
• Option 4: grep . file.txt > output.txt

Remove empty lines from file.txt using Powershell script on Windows