How to extract numbers from a string?

Question

I have string contains a path

string="toto.titi.12.tata.2.abc.def"

I want to extract only the numbers from this string.

To extract the first number:

tmp="${string#toto.titi.*.}"
num1="${tmp%.tata*}"

To extract the second number:

tmp="${string#toto.titi.*.tata.*.}"
num2="${tmp%.abc.def}"

So to extract a parameter I have to do it in 2 steps. How to extract a number with one step?

Answer 1

You can use tr to delete all of the non-digit characters, like so:

echo toto.titi.12.tata.2.abc.def | tr -d -c 0-9