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I need to multiply a column in a file with float numbers, say with (1.0 + 0.25)

I have a extracted column 3 ( with Numbers) with awk command from file file1.txt

awk '{ print $3 }' file1.txt > coloumn1

1.0

1.2

1.3

I want to multiply all column values with (1.0 + 0.25)to achieve the following values. requirement is to use different p1 values. p1 is 1.1

( 1.0*(p1+0.25))  
( 1.2*(p1+0.25))  
( 1.3*(p1+0.25))

1.250

1.500

1.625

My script is

#bin/bash
p1=1.0
val=`echo $p1 + 0.25 | bc`
awk -F, '{$1*=$val}1' OFS=, coloumn1 > coloumn_mod

But above awk command is not returning the expected result ,

Could you please help correcting the above command ?

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Partha
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    Please note that the reason why awk doesn't return the expected result is that because in the single quotes ' ... ' in which you have enclosed the program (as is recommended), shell variables are not expanded. If you are interested to learn more about this (and the peculiarities of it), see here on how to import shell variables into awk. – AdminBee Nov 19 '20 at 09:37
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    Does this answer your question? Use a shell variable in awk – thanasisp Nov 19 '20 at 23:53

1 Answers1

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awk -v p1='1.0' '{ printf("%.3f\n", $0*(p1+0.25) ) }' infile

if there are more than a column in your input file and say they are separated by comma character and you want do this on 3rd column, you can use:

awk -F, -v p1='1.0' '{ printf("%.3f\n", $3*(p1+0.25) ) }' infile

in awk, $0 represents the entire record/line, $1 first field/column, $2 second field/column, $3 third field and so on; where fields splits on the default whitespace character (Tabs/Spaces) or you can redefine it by -F or -v FS= or within code-blocks as well.

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