Adding columns with awk. What is wrong with this awk command?

Question

I want to add two columns to a file with ~10,000 columns. I want to insert as the first column the nr 22 on each row. Then I want the original first column as the second column, then as the third column I want to insert the line nr (NR), and after that I want the rest of the original columns to be printed. I thought I could do that with the following awk line:

awk '{print 22, $1, NR; for(i=2;i<=NF;++i) print $i}' file

It prints the first three columns (22, $1, NR) well, but after that, there is a new line started for each value, so the file is printed like this:

22 $1 NR
$2
$3
$4
etc...

instead of:

22 $1 NR $2 $3 $4 etc...

What did I do wrong?

Fredrik Pihl · Accepted Answer · 2012-03-22 11:59:44Z

4

How about using printf instead since print adds a newline.

awk '{printf("%d, %d, %d, ", 22, $1, NR); for(i=2;i<=NF;++i) printf("%d, ", i)}' file

Or you can play with the ORS and OFS, the Output Record Separator and the Output Field Separator. Normally you add those in a BEGIN statement like this:

awk 'BEGIN { ORS = " " } {print 22, $1, NR; for(i=2;i<=NF;++i) print $i}{print "\n"}' file

Note that an extra printf "\n" is needed, else everything ends up on one line...

Read more in gawk manual output separators

edited Mar 22, 2012 at 11:59

answered Mar 22, 2012 at 11:51

Fredrik Pihl

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kev · Accepted Answer · 2012-03-22 11:50:13Z

1

For more precise control over the output format than what is provided by print(which print a newline by default), use printf.

answered Mar 22, 2012 at 11:50

kev

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