Question

I want to extract a version number from some strings in bash without using too much additional packages. So far I tried sed.

Here is the API :

3.81-8.1ubuntu1.1    should give :  3.81
2.68-1ubuntu2        should give :  2.68
1:1.11.3-1ubuntu2    should give :  1.11.3

And here is my sed command so far:

echo ... | sed -r 's/.*([0-9\.]+).*/\1/'

However, the opening .* is too greedy, especially with the last case. I’ve tried some .*? and .\{-} without any success.

I can do it in two passes, but I would rather learn how to do it in one.

Answer 1

is this ok for you?

 grep -Po "[\d\.]*(?=-)" file

example:

kent$  cat tt
3.81-8.1ubuntu1.1
2.68-1ubuntu2
1:1.11.3-1ubuntu2

kent$  grep -Po "[\d\.]*(?=-)" tt
3.81
2.68
1.11.3