How to add some data from BASH variables to the beginning of all lines in a CSV file?

Question

I need to add $author \t $title \t to the beginning of every line in a tab-seperated CSV file. This is an example of what the file looks like originally:

0001 This is a line. 0002 This is another line. 0003 This is yet another line.

After editing, and assuming $author is set to "Lewis Carroll" and $title set to "Through the Looking Glass", the output would look just like this:

Lewis Caroll Through the Looking Glass 0001 This is a line. Lewis Caroll Through the Looking Glass 0002 This is another line. Lewis Caroll Through the Looking Glass 0003 This is yet another line.

I tried the following attempts with awk, but it does not work as expected, and $author and $title do not appear to be added anywhere in the file:

awk -F'\t' '{ print "$author\t$title\t" $0 }' file.txt awk -F"\t" '{ print $author \t $title \t $0 }' file.txt

How can I add some data, containing BASH variables, as cells, to the beginning of all of the lines in a tab-seperated CSV file?

devnull · Accepted Answer · 2014-03-15 05:42:10Z

Not sure how you're doing, but it should work:

awk -vauthor="Lewis Carrol" -vtitle="Through the Looking Glass" '{print author, title, $0 }' OFS='\t' inputfile

_{Were you attempting to pass shell variables instead?}

For the case at hand, you are better off using sed, though:

sed "s/^/${author}\t${title}\t/" filename

(Remember to use double quotes)

Yes, the $author is retrieved from elsewhere author="$(echo $line | awk -F@ '{print $2}')" earlier in the script.
@Village You need to pass variables to awk. If it's a shell variable, say: -vauthor="$author" -v title="$title"

Amit · Accepted Answer · 2014-03-15 05:43:27Z

sed "s/^/${author}\t${title}\t/" file.txt

You can also add -i option to sed for in-place update

sed -i "s/^/${author}\t${title}\t/" file.txt

BMW · Accepted Answer · 2014-03-15 12:04:54Z

Pure shell

#!/usr/bin/env ksh author="Lewis Carrol" title="Through the Looking Glass" while read -r line do printf "${author}\t${title}\t${line}\n" done < file

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