How to install/replace on Android without using Eclipse

Question

A buddy sent me a later version of an .apk file. I already had the earlier version on my device.

When I tried to adb install the file, I got this:

$ adb          


        

Answer 1

You need to supply the -r key:

adb install -r myapp-release.apk

This has been already discussed: Why does adb install fail?