data/
├── input.txt
├── Makefile

count.cache: input.txt
    cat $^ | xargs seq >$@

echo '5'>input.txt

make

cat input.txt | xargs seq >count.cache

cat count.cache
1
2
3
4
5

make
make: `count.cache' is up to date.

echo '10'>input.txt

make
cat input.txt | xargs seq >count.cache

cat count.cache
1
2
3
4
5
6
7
8
9
10