C:\chas_sandbox>for %f in (a b c d) Do echo %f>>alpha.txt

C:\chas_sandbox>echo a 1>>alpha.txt

C:\chas_sandbox>echo b 1>>alpha.txt

C:\chas_sandbox>echo c 1>>alpha.txt

C:\chas_sandbox>echo d 1>>alpha.txt

C:\chas_sandbox>perl -le "open my $fh_in, '<', 'alpha.txt'; open my $fh_out, '>>
', 'alpha.txt';while (<$fh_in>) {chomp;print $fh_out chr(ord($_)+4); last if $_
eq 'v'}"

C:\chas_sandbox>type alpha.txt
a
b
c
d
e
f
g
h