modify first column

Shell Programming and Scripting
1

Hi,

I am use to using awk and sed. This time I have a file that has multiple columns. It looks like this:

4  6  7  8
5  4  3  2
3  2  6  9

I want to add chr to column 1 only so it looks like this:

chr4  6  7  8
chr5  4  3  2
chr3  2  6  9

The file is tab seperated.

Thanks

Phil

2 
awk '{ $1="chr" $1; } 1' < datafile > outfile
3

make sure you specify the OFS (as you're re-eval-ing the record):

awk '{ $1="chr" $1; } 1' OFS=\t'  < datafile > outfile
4 
awk '{$0="chr" $0}1' infile > outfile

sed -i 's/^/chr/' file
5 
bash-3.00$ sed 's/^./chr&/' /tmp/myfile
chr4  6  7  8
chr5  4  3  2
chr3  2  6  9

use sed -i to save the file with changes

6

alternate awk solution

awk '{print "chr" $0}' OFS=\t inptufile > outfile