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serverstackqns
Asked: 2022-11-12 05:10:47 +0800 CST

Variable in AWK

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How can I add a variable within awk command? below is my command:

cat /home/ubuntu/test/copy.txt | awk 'NR==21{print ".host = "$line";"}1'

$line is basically an IP address which is retrieved from a text file. With the above command the output looks like

.host = ;

Any immediate help would be really appreciated.

Format of copy.txt

backend default {
#.host = value; need to be here
.port = "8080";
}
ubuntu

1 Answers

  1. Best Answer

    The variables in awk can be transferred from shell on this way:

    awk -v variable=$line '.....

    and used inside on this way:

    awk -v line1=$line 'NR==21 {print ".host = "line1";"}1'

    The variable should be set beforehand in bash so the things become:

    line=192.168.0.10
awk -v line1=$line 'NR==21 {print ".host = "line1";"}1' /path/to/file ...

    Also you do not need cat, just use this way:

    awk '....' /home/ubuntu/test/copy.txt

    To store the output in a file you should use something like:

    awk '....' /home/ubuntu/test/copy.txt >/home/ubuntu/test/new_copy.txt

    and the result will be stored in /home/ubuntu/test/new_copy.txt

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