Insert text at specific line number

Question

I'm working on a bash script that will split the contents of a text document depending on the data in the line.

If the contents of the original file were along the lines of

01 line
01 line
02 line
02 line

How can I insert into line 3 of this file using bash to result in

01 line
01 line
text to insert
02 line
02 line

I'm hoping to do this using a heredoc or something similar in my script

#!/bin/bash

vim -e -s ./file.txt <<- HEREDOC
    :3 | startinsert | "text to insert\n"
    :update
    :quit
HEREDOC

The above doesn't work of course but any recommendations that I could implement into this bash script?

https://stackoverflow.com/questions/6537490/insert-a-line-at-specific-line-number-with-sed-or-awk — giannis christofakis, Aug 30 '18 at 10:58

Zombo · Accepted Answer · 2020-05-03T20:38:45.657

22

You can use the POSIX tool ex by line number:

ex a.txt <<eof
3 insert
Sunday
.
xit
eof

Or string match:

ex a.txt <<eof
/Monday/ insert
Sunday
.
xit
eof

edited May 03 '20 at 20:38

answered Apr 17 '16 at 04:47

Zombo

thrig · Answer 2 · 2016-03-22T21:19:12.473

15

sed would be a traditional choice (GNU sed probably has an easier form than this).

$ cat input
01 line
01 line
02 line
02 line
$ sed '2a\
text to insert
' < input
01 line
01 line
text to insert
02 line
02 line
$

Or, being extremely traditional, ed (bonus! in-place edit without the unportable sed -i form).

$ (echo 2; echo a; echo text to insert; echo .; echo wq) | ed input
32
01 line
47
$ cat input
01 line
01 line
text to insert
02 line
02 line
$

(This has nothing to do with bash.)

edited Mar 22 '16 at 21:19

answered Mar 22 '16 at 14:22

thrig

2

added bonux replace echo text to insert by cat file-to-insert.txt – Archemar Mar 22 '16 at 15:06
1

At least with bash, instead of all those echos, you could use printf '%s\n' 2 a 'text to insert' . wq – evilsoup Mar 22 '16 at 22:58

score 13 · Answer 3 · answered Mar 23 '17 at 04:24

13

$ awk 'NR==3{print "text to insert"}1' a.txt
01 line
01 line
text to insert
02 line
02 line

answered Mar 23 '17 at 04:24

Kamaraj

can be used as awk -i inplace '...' for a one-line equivalent of the sed -i solution. See https://stackoverflow.com/questions/16529716/ – eddygeek Mar 04 '21 at 18:50

score 9 · Answer 4 · answered Mar 22 '16 at 14:20

9

How about something like:

head -n 2 ./file.txt > newfile.txt
echo "text to insert" >> newfile.txt
tail -n +3 ./file.txt >> newfile.txt
mv newfile.txt file.txt

answered Mar 22 '16 at 14:20

mkomarinski

2

Strange but interesting idea +1 – Satoshi Nakamoto Jun 07 '19 at 20:27
head -n 5 ./pom.xml > pomnew.xml echo "war" >> pomnew.xml tail -n +6 ./pom.xml >> pomnew.xml mv pomnew.xml pom.xml – Kasthuri Shravankumar Dec 05 '22 at 05:03
You may compact this like this: (head -2 file.txt; echo row three ; tail -3 file.txt) > newfile.txt (using Gnu Linux tools). – user unknown Feb 23 '23 at 21:32

wolfrevo · Answer 5 · 2023-02-23T16:29:38.310

1

Try the following:

Your original file

$ cat <<'EOF' > file.txt
01 line
01 line
02 line
02 line
EOF

insert into line 3 using a heredoc.

$ cat <<'EOF' | sed -i "3r /dev/stdin" file.txt
text to insert
EOF

you get this result

$ cat file.txt
01 line
01 line
text to insert
02 line
02 line

UPDATED: Following the comment of @Kusalananda

edited Feb 23 '23 at 16:29

answered Feb 23 '23 at 13:39

wolfrevo

5

Brevity is acceptable, but fuller explanations are better. Also note that the user gives a specific example use case in their question. It would benefit your answer (and your duplicated answer here) to actually use the user's sample documents. – Kusalananda Feb 23 '23 at 14:03
1

@Kusalananda: Thanks for your comment. I've updated my answer. – wolfrevo Feb 23 '23 at 16:30

5 Answers5