Replace a block of numbers in sed
Solution 1:
You don't need the +. Just use the following:
echo "fdsafdsa 32432 dsafdas" | sed 's/[0-9]/#/g'
[0-9] will already match all digits, and replace every single one with #.
Since + is extended syntax, you could also do:
echo "fdsafdsa 32432 dsafdas" | sed -E 's/[0-9]+/#/g'
to replace the whole block of digits with one #.