I'm afraid it depends on the device. On a really smart device, the unit may actually login as a LAN client, to the target PC would be a network share and you could simply do a file copy.
The next level down would be where the device acquires a TCP/IP socket on the USB interface. In that case, you'd have to have some sort of client program on the mobile and a corresponding server program on the target PC. This is the same basic idea as on smarter devices, except that instead of getting a client program for free, you have to write your own (or find one).
Below that level, you're probably stuck with doing extremely specialized low-level stuff. Fortunately, all the smartphones I've worked with have had at least some basic TCP/IP support.
An IDE is no substitute for an Intelligent Developer.
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