How to copy an entire line which matches the string and paste right after it?

Question

I am trying to search for a particular line in a file using grep command and I am successful doing that. Now I want to copy the entire line to a new line right after the original line. In other words, the original line should be followed by the new line with same content.

For example: Original data:

Apple 

Samsung

Nokia

HTC

Say if I want the new data to look like

Apple

Samsung

Samsung

Nokia

HTC

I tried grep and pipe with sed and I failed. Can anyone please help me with this?

Thanks

grep input.txt This will read the entire line if it matches with the string. Now I want to copy the buffer into a new line which comes after the original line — Harish, Mar 02 '17 at 22:52

Walter A · Answer 1 · 2017-03-02T23:25:45.067

2

With sed you can turn off printing lines by default with -n and display lines with p. Using this information will show the solution

sed '/Samsung/p' yourfile
# Or, when you want to match the whole line
sed '/^Samsung$/p' yourfile

edited Mar 02 '17 at 23:25

answered Mar 02 '17 at 23:16

Walter A

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What does `-n` have to do with this question? – glenn jackman Mar 03 '17 at 02:02
@glennjackman This is the first time I use the option `p` without `-n`. For people who do not know the `p` option it is a small hint how `p` can be used in other situations. – Walter A Mar 03 '17 at 08:13

score 2 · Answer 2 · answered Dec 09 '20 at 11:51

To copy the entire line matching pattern, and to past it on the new line, right after that:

sed -i $'s/.*Samsung.*/&\\\n&/' file

The output:

Apple
Samsung
Samsung
Nokia
HTC

To output the result to another file.

sed $'s/.*Samsung.*/&\\\n&/' file > anotherfile

score 0 · Answer 3 · answered Mar 02 '17 at 22:22

For a file input.txt with the contents

Apple
Samsung
Nokia
HTC

You can do inline replacement a duplicate the lines 'Samsung' like this:

sed -i 's/\(Samsung\)/\1\n\1/' input.txt

The parentheses capture the word, then \1 puts it back twice with a newline in between.

score 0 · Answer 4 · edited May 23 '17 at 12:32

0

Use this sed:

sed $'s/Samsung/&\\\n&/' input.txt

Outputs:

Apple
Samsung
Samsung
Nokia
HTC

See also:

How to insert a newline in front of a pattern?

edited May 23 '17 at 12:32

Community

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answered Mar 02 '17 at 22:33

codeforester

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Hi codeforester, thank you for your help. I gave a very simple example as the data but in my case I have a pretty lengthy line and it is not convenient to type the entire line each as I have to do this multiple times in my file. I was thinking to use grep, match the pattern, and then copy the entire line. Any thoughts? – Harish Mar 02 '17 at 22:41
Or this sed: `sed '/Samsung/ {h;G}' file` – glenn jackman Mar 03 '17 at 02:05

score 0 · Accepted Answer · answered Mar 03 '17 at 00:29

0

This might work for you (GNU sed):

sed '/pattern/H;//G' file

If the pattern can occur more than once:

sed 'x;z;x;/pattern/H;//G' file

answered Mar 03 '17 at 00:29

potong

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score 0 · Answer 6 · answered Mar 03 '17 at 02:06

0

For completeness:

awk '/Samsung/ {print}; {print}' file
perl -pe 'print if /Samsung/' file

answered Mar 03 '17 at 02:06

glenn jackman

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How to copy an entire line which matches the string and paste right after it?

6 Answers6