CODEWITHSUNDEEP
linuxbashgrep
user3631848
user3631848

Reputation: 483

Add an extra column after grep content

I understand that grep can extract the specific content from a file line by line. Just wondering how can add another column before or after each line as an index. For example: 

grep "aaa"  text.txt > tmp.txt

In the tmp.txt file, we can see the content as follows, 

aaawekjre
qejrteraaa
wrgeaaaere

However, I would like to add a specific index as an extra column. Therefore, the tmp.txt might look like this:

John aaawekjre
John qejrteraaa
John wrgeaaaere

Upvotes: 3

Views: 2047

Answers (3)

John1024
John1024

Reputation: 113834

$ sed -n '/aaa/ s/^/John /p' text.txt
John aaawekjre
John qejrteraaa
John wrgeaaaere

How it works

  • -n

    This tells sed not to print anything unless we explicitly ask it to.

  • /aaa/ s/^/John /p

    This selects lines that contain aaa. For those lines, we do a substitution (s/^/John /) to put John at the beginning of the line and we print the line (p).

    In this way, lines that do not contain aaa are never printed. Thus, there is no need for a separate grep process.

Upvotes: 6

Mustafa DOGRU
Mustafa DOGRU

Reputation: 4112

try this

   grep "aaa"  text.txt | awk '{print "John " $0}' > tmp.txt

Upvotes: 2

anubhava
anubhava

Reputation: 785146

You can use awk:

awk '/aaa/{print "John", $0}' text.txt > tmp.txt

Upvotes: 7

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