Question

I have a input file that I need to replace first character of column 3 (“) with (“S)

File1:

1      2      "45554323"      p      b  
2      2      "34534567"      f      a  
3      3      "76546787"      u      b  
2      4      "56765435"      f      a

Result:

1      2      "S45554323"      p      b  
2      2      "S34534567"      f      a  
3      3      "S76546787"      u      b  
2      4      "S56765435"      f      a  

I tried

awk '{gsub(substr($3,0,1),"\"S"); print}'

but it gives me $3 with S at begin and the end, like "S45554323"S. Can you give me a solution?

Answer 1

Try with:

awk 'BEGIN { OFS = "\t"; } { sub( /[[:digit:]]/, "S", $3 ); print }' infile

That yields:

1       2       "S5554323"      p       b
2       2       "S4534567"      f       a
3       3       "S6546787"      u       b
2       4       "S6765435"      f       a

Or with sed:

sed -e 's/\("\)[0-9]/\1S/' infile