Concatenating Files And Insert New Line In Between Files

Question

You can do:

for f in *.txt; do (cat "${f}"; echo) >> finalfile.txt; done

Make sure the file finalfile.txt does not exist before you run the above command.

If you are allowed to use awk you can do:

awk 'FNR==1{print ""}1' *.txt > finalfile.txt

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.txt

In 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

This works in Bash:

for f in *.txt; do cat $f; echo; done

In contrast to answers with >> (append), the output of this command can be piped into other programs.

Examples:

• for f in File*.txt; do cat $f; echo; done > finalfile.txt
• (for ... done) > finalfile.txt (parens are optional)
• for ... done | less (piping into less)
• for ... done | head -n -1 (this strips off the trailing blank line)