Duplicate Rows in Text File

For 3 times you can just run:

cat file file file > new_file

And here is a trick if you're lazy like me and you don't want to re-type the file name N times. Type cat then the filename, Press Ctrl+W, then Ctrl+YSpace N times, finally type > new_file.

However it's a better idea to use a simple "loop" in combination with cat command.

• 3 times example:

  for i in {1..3}; do cat file >> new_file; done
  

Or as you asked in comments:

limit=3
for ((i=0; i<limit; i++)); do cat file >> new_file; done

Change '3' to any number you want.

Result:

jplg3350.18i
jplg3360.18i
jplg3370.18i
jplg3350.18i
jplg3360.18i
jplg3370.18i
jplg3350.18i
jplg3360.18i
jplg3370.18i