Concatenating Files And Insert New Line In Between Files
If you have few enough files that you can list each one, then you can use process substitution in Bash, inserting a newline between each pair of files:
cat File1.txt <(echo) File2.txt <(echo) File3.txt > finalfile.txt
If it were me doing it I'd use sed:
sed -e '$s/$/\n/' -s *.txt > finalfile.txtIn this sed pattern $ has two meanings, firstly it matches the last line number only (as a range of lines to apply a pattern on) and secondly it matches the end of the line in the substitution pattern.
If your version of sed doesn't have -s (process input files separately) you can do it all as a loop though:
for f in *.txt ; do sed -e '$s/$/\n/' $f ; done > finalfile.txt