qemu -квм отсутствует

c-shellможет стать здесь настоящим спасителем:

% foreach line ( "`cat./input.txt`" )
   printf '%s\t%s\t' ${line:q} ${line:r:t:q}
   printf '%smain\n' ${line:r:t:q}
end

Другими методами являются:

$ perl -F/ -pale '
   my($t) = $F[-1] =~ /([^.]+)/;
   $_ = join "\t", $_, $t, "${t}main" if /\S/;
'./input.txt

$ sed -Ee '
   s|([^/.]+)\.[^/.]+$|&\t\1\t\1main|;t
   s|([^.]+)\.[^.]+$|&\t\1\t\1main|;t
   s|([^/]+)$|&\t\1\t\1main|
'./input.txt

Результаты:

/myhome/new1/myfiles/test2.sh   test2   test2main
/myhome/new3/myfiles/test1.sh   test1   test1main
/myhome/new2/myfiles/test4.sh   test4   test4main
/myhome/new/myfiles/test5.sh    test5   test5main

Примечания:

o We have to be verbose as we need to cover the various possible cases that may arise.
o GNU sed is needed.