Sed_remove_empty_lines.txt

sed '/^\s*$/d'input > output

Alternativas:

sed
'/^[[:space:]]*$/d'
'/^\s*$/d'
'/^$/d'
-n '/^\s*$/!p'


grep
-v '^\s*$'
-v '^[[:space:]]*$'


awk
/./
'NF'
'length'
'/^[ \t]*$/ {next;} {print}'
'!/^[ \t]*$/'