move to a specified location in a text file and overwrite

Question

hi guys

i have a text file with the contents as follows

code:x:y

2346:1:0

3456:2:6

2345:3:7

4567: 4:1

3456:5:3 

i need to read from beginning of file and check if "4567"is present in file ,if present i need to move to that matched row 'y' column and increment the value....that is increment 1 in my above file and write it back in the same location.

 

please help

thanks