Question

Given an input file containing one single number per line, how could I get a count of how many times an item occurred in that file?

cat input.txt
1
2
1
3
1
0

desired output (=>[1,3,1,1]):

cat output.txt
0 1
1 3
2 1
3 1

It would be great, if the solution could also be extended for floating numbers.

Answer 1

You mean you want a count of how many times an item appears in the input file? First sort it (using -n if the input is always numbers as in your example) then count the unique results.

sort -n input.txt | uniq -c