Make a line blank, by returning everything on that line down in bash

Question

I want to alter a text file. Let's say I have some text on line 22, and I want to make line 22 blank and move down the text on line 22 down to line 23. To illustrate, I want to turn this (printf 'Some %d text\n' {1..23}):

Some 1 text
Some 2 text
Some 3 text
Some 4 text
Some 5 text
Some 6 text
Some 7 text
Some 8 text
Some 9 text
Some 10 text
Some 11 text
Some 12 text
Some 13 text
Some 14 text
Some 15 text
Some 16 text
Some 17 text
Some 18 text
Some 19 text
Some 20 text
Some 21 text
Some 22 text
Some 23 text

into this:

Some 1 text
Some 2 text
Some 3 text
Some 4 text
Some 5 text
Some 6 text
Some 7 text
Some 8 text
Some 9 text
Some 10 text
Some 11 text
Some 12 text
Some 13 text
Some 14 text
Some 15 text
Some 16 text
Some 17 text
Some 18 text
Some 19 text
Some 20 text
Some 21 text
Some 22 text

Some 23 text

How would I do this?

Answer 1

sed -i '21 a\
' yourfile

21 is previous line number full example on line 1 to append (a) blank line after line 1 :

francois@zaphod:~$ cat toto
Some text
Some more text
Some other text
francois@zaphod:~$ sed -i '1 a\
' toto
francois@zaphod:~$ cat toto
Some text

Some more text
Some other text
francois@zaphod:~$

then file is 4 lines long (including the blank one)

Answer 2

With the standard editor ed, just print the corresponding commands to its input:

printf '%s\n' 22a '' . w q | ed -s file

1. Append after line 22
2. (blank line)
3. . -- end the appended input
4. write the file to disk
5. quit ed

Alternatively, insert before line 23 with 23i instead of 22a.

Answer 3

You can use the following with sed:

$ sed -e '22{x;G;}' file

This will put an empty line (a newline) before the 22nd line. The prior contents of the 22nd line will be pushed down. Note though that the contents of the hold space will be modified by this operation. To preserve , use the below variation:

$ sed -e '22{x;p;x;}' file 

Or with the awk / perl utilities:

$ awk 'NR==22{$0 = RS $0}1' file

$ perl -pe '22..22&&s/^/\n/' file