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up vote 2 down vote favorite

I need to a add a column in CSV file from an array using awk.

For example,

input.csv

a,10
b,11

array = (100 200)

output.csv should look like

a,10,100
b,11,200

I tried this command but it does not work

awk -F"," 'BEGIN { OFS = "," } {for (x in array) $3=array[x]; print}' input.csv> output.csv
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2 Answers 2

up vote 3 down vote

Do you have to use awk for this? The paste utility was designed exactly for this sort of thing. Assuming array is a shell array:

array=(100 200)
printf "%s\n" "${array[@]}" | paste -d, input.csv - > output.csv

The printf is simply to put each array member on a new line. paste then pastes together input lines from input.csv and - (i.e. the piped output from printf), using a comma as a delimiter.

If your array happens to be a newline separated file, e.g. array.txt:

100
200

then it is even easier:

paste -d, input.csv array.txt > output.csv
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up vote 0 down vote

The problem is that shell variables (including arrays) are not available inside awk. You need to pass them explicitly via -v option. Moreover you cannot pass the whole array, but you can put array into single variable and split it inside awk:

awk -va="$(echo "${array[@]}")" 'BEGIN{OFS=FS=","; split(a,b," ")}{print $0,b[NR]}' input.csv

This will work as long as you don't have spaces inside array elements.

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actually you can stackoverflow.com/a/15787182/2002471 –  chicks Aug 28 at 4:50
    
Thanks very much. –  Rauf Aug 31 at 12:59

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