How do I assign the line number to each string present in a file

Question

F1.txt

tom a b c d e boy

bob a b c sun

harry a c d e girl

result

F2.txt

tom1 a1 b1 c1 d1 e1 boy1

tom2 a2 b2 c2 sun2

tom3 a3 c3 d3 e3 girl3

Hello everyone, I am quite new to Perl,can you kindly help me out with this new problem of mine. I have a file F1.txt, my job is to assign numbers after each string in a file according to its line number as shown in an example above. I have so far just managed to assign a number to each of the lines with this Perl one-liner

perl -pe '$_= ++$a." $_" if /./'

Answer 1

Maybe as follows:

perl -pe 's/(?<=\w)\b/$./g;'

Answer 2

The special variable $. holds the current line number.

The regex /(?<=\w)\b/g matches each end of a word (or a number or underscore). Or, more precise, a word boundary preceded by a "word" character which we don't include in our match. The \b assertion has zero width. Use the regex s/(?<=\S)(?=\s|$)/$./g to put a line number after each non-space sequence.

We can use the substitution operator s///g to append the line number in this way:

echo -e "a b\nc d" | perl -ne 's/(?<=\w)\b/$./g; print'

prints

a1 b1
c2 d2

Answer 3

in a one-liner:

perl -pe 's/(?<=\w)\b/$./g' F1.txt >F2.txt