Removing last blank line

Try ${/^$/d;} this will only match an empty line if it is the last line of the file.

Update: for your second question, just remove the 1 before the s, i.e.: sed -i 's/^[^0-9]*//' combined.csv

Found this ages ago somewhere and saved the snippet. Do not ask me how it works:

perl -i -pe "chomp if eof" combined.csv