regex - Use 'sed' to find a number in line -

i trying use unix sed command find line numbers match particular regular expression. pattern of file below

murali : 20 # krishna: 21 $ hari: 22 @ murali : 23 # 

i need output numbers below using sed command

20 21 22 23 

can please me regular expression sed.

how

$ cat input murali : 20 # krishna: 21 $ hari: 22 @ murali : 23 #  $ sed -r 's/^[^0-9]+([0-9]+).*/\1/g' input 20 21 22 23 

• [^0-9]+ matches other digit

• ([0-9]+) matches digits, captured in group 1

• .* matches rest