os independent keyboard input listener service (windows, linux and mac)

We need an os independent keyboard input listener service (windows, linux and mac). Basically we have a usb scanner connected to a computer that scans a bar code for a cash register system. When a certain type of bar codes (customer cards) is being scant, we want to execute some command lines and open a browser with a special url. Luckily USB-Scanners simulate USB-keyboards. A scan always end with a "enter" like a newline \n (in windows). So your task is to provide an OS independent C++ input listener that waits in the background for a matching regular expression and then executes a given command line. Example on windows OS: Scanner gives input like 12dc@sdsrX4\n that is a special code and then the command line [login to view URL] -para1 [login to view URL]"12dc@sdsrX4" will be executed. The program should be configurable via a config file. In this config file there should be a set of rules (regular expressions) and resulting actions (command lines) Example config: rule1 = [a-zA-Z0-9]{4}@[a-zA-Z0-9]{5,6}[@]{0,1} com1 = [login to view URL] -para1 [login to view URL]"%s" where %s is the matching code. So rule1 is basically 4 chars ranging from a to z,A to Z or 0 to [login to view URL] the 5th char is an @ and then followed by 5 or 6 normal chars and an optional @ at the end. So in total, the code comprises 11 characters. A dot will never be in the code, what will help to exclude email addresses which are accidentally scanned. So 12dc@sdsrX4 or AAAA@BBBBB@ are valid codes. Please ask if you have any questions. Also see: [login to view URL] for a windows example for building a similar program [login to view URL] for the regular expressions