Shell Programming and Scripting

for example
I have 2 lines in flat file ,I want to add another 100 lines with different account numberS.

accno    am1   amt2 amt3
102345  1000  200     300

102346  1000   200      300

o/p

accno    am1   amt2    amt3
102345  1000  200     300
102346  1000   200     300
102347  1000   200     300
102348  1000   200     300
..
..
102445  1000   200     300

$
$ cat input.txt
102345  1000  200     300
102346  1000  200     300
$
$
$ perl -ne 'print; $x= substr($_,0,index($_," ")); $y = substr($_,index($_," "));
>           END {foreach $i(1..99) {print $x+$i,$y}}' input.txt
102345  1000  200     300
102346  1000  200     300
102347  1000  200     300
...
... <snipped output for brevity>
102443  1000  200     300
102444  1000  200     300
102445  1000  200     300
$
$

$ cat input.txt
102345  1000  200     300
102346  1000  201     300

o/p
102345  1000  200     300
102346  1000  201     300
102347  1000  202     300
102348  1000  203     300
102349  1000  204     300
..............................

perl -ne 'print; $x= substr($_,0,index($_," ")); $y = substr($_,index($_," "));
>           END {foreach $i(1..10) {print $x+$i,$y}}' input.txt



1.10000000,306829
2.1
3.1
4.1
5.1
6.1
7.1
8.1
9.1
10.1

Expecting o/p

1.10000000,306829
1.10000001,306829
1.10000002,306829
1.10000003,306829
1.10000004,306829
......

$
$ perl -ne 'print; @x = split/,/; END {foreach $i(1..5) {print $x[0]+$i/100000000,",",$x[1]}}' input.txt
1.10000000,306829
1.10000001,306829
1.10000002,306829
1.10000003,306829
1.10000004,306829
1.10000005,306829
$