Shell Programming and Scripting

I am just trying to insert the word "Index" using awk. The below is close but seems to add the word at the end and I can not get the syntax correct to add from the beginning. Thank you .

Code:

awk -F'\t' -v OFS='\t' '{ $-1=$-1 OFS "Index"}$1=$1' file

current output

Code:

Chr    Start    End    Ref     Index
chr1    949608    949608    G    A     1

desired output

Code:

Index     Chr    Start    End    Ref     Index
  1       chr1    949608    949608    G    A

Code:

awk -F'\t' -v OFS='\t' '{$0=((NR==1) ? "Index" : (NR - 1)) OFS $0} 1' file

Thank you very much .

You might also try:

Code:

awk -F'\t' -v OFS='\t' '{print (NR==1) ? "Index" : NR - 1, $0}' file

but, note that the sample input you provided does not contain any <tab> characters. If none of the data in your fields contains whitespace characters and you have one or more <space> and <tab> characters separating fields in your input file, you might want to leave the input field separator unspecified to produce <tab> separated output:

Code:

awk -v OFS='\t' '{$1 = $1; print (NR==1) ? "Index" : NR - 1, $0}' file

It is also strange that your input file header line seems to have four fields while the rest of your input file lines seem to have five fields???