Как в bash разделить числа в первом столбце файла?

[~]# cat test.txt
22 xxxxxxxxxxxxxxxx
2 yyyyyyyyyyyyyyyyyyyyyy
2 qqqqqqqqqqqqqqqqqq
6 xxxxxxxxxxxxxxxxxxxx
4 ffffffffffffffff
4 9718947ddddddddddddddddddd
4 2351273512735 0989089089
4 lllllllllllllllllllllllll
[~]# cat test.txt | awk '{$1=$1/2; print}'
11 xxxxxxxxxxxxxxxx
1 yyyyyyyyyyyyyyyyyyyyyy
1 qqqqqqqqqqqqqqqqqq
3 xxxxxxxxxxxxxxxxxxxx
2 ffffffffffffffff
2 9718947ddddddddddddddddddd
2 2351273512735 0989089089
2 lllllllllllllllllllllllll

cat file | perl -ne '/^(\d+)/; $x = int($1)/2; s/^\d+/$x/; print'

cat ашду | perl -ne '/^(\d+)(.+)/; print "".($1/2)."$2\n"'