Getting numbers from a string with grep

Question

I came with another simple question...

I got a string with a substring in the format xx:xx:xx where the x's are numbers. I want to extract that substring including the ":" symbol, so my output would be "xx:xx:xx".

I think it can be done with a grep -Eo [0-9], but im not sure of the syntax... Any help?

Solution

echo "substring in the format 12:43:37 where the x's are numbers" | 
      grep -o '[0-9:]*'

Output:

12:43:37

If you have other numbers in the input string you can be more specific:

grep -o '[0-9]*:[0-9]*:[0-9]*'

even:

grep -o '[0-9][0-9]:[0-9][0-9]:[0-9][0-9]'

Comments

[Ghost]

Doesn't work... it outputs nothing, i also tried ur example and nothing too.

[Ghost]

Did that, and the output is nothing, also tested the examples as i said and same result

[perreal]

the code works on ideone, and it works on my box. If it doesn't produce any output on your side then you might have some slightly different input. Can you post what you have tried?