how to cat an input file to an output file, adding a blank line between every two lines of the input file (double spacing)?

Question

Without using SED, is there shell script to copy the content from an input file to a output file, adding a blank line between every two lines of the input file (double spacing)? I

_"without using sed"_ smells like homework... – don_crissti Dec 03 '16 at 19:15 — don_crissti, Dec 03 '16 at 19:15
*is there shell script...* easy answer : yes. – steve Dec 03 '16 at 19:36 — steve, Dec 03 '16 at 19:36

score 0 · Answer 1 · answered Dec 03 '16 at 18:55

0

IFS=""
while read -r LINE
do
  echo "$LINE"
  echo
done

If it bothers you that it adds a blank line after the last line, one can do:

IFS=""
FIRST=y
while read -r LINE
do
  if [ "$FIRST" != "y" ]
  then
    echo
  fi
  FIRST=n
  echo "$LINE"
done

answered Dec 03 '16 at 18:55

DepressedDaniel

4,169
12
15

steve · Answer 2 · 2016-12-03T19:35:20.940

0

This appears to achieve what you're after.

If NR (line number) is divisible by 2, tag an extra newline at the end. And then print the line.

$ awk 'NR%2==0{$0=$0"\n"}1' foo.txt
line1
line2

line3
line4

line5
$

If it's merely a blank line between every line, use this

$ awk '{print $0,"\n"}' foo.txt
line1

line2

line3

line4

line5

$

edited Dec 03 '16 at 19:35

answered Dec 03 '16 at 19:21

steve

21,582
5
48
75

"between every two lines" not every two lines. -1. – Dec 03 '16 at 19:23
If?! Come on... – Dec 03 '16 at 19:37

how to cat an input file to an output file, adding a blank line between every two lines of the input file (double spacing)?

2 Answers2