agvtool stands for Apple-generic versioning tool for Xcode projects

You can modify app version string and build number string without 3rd party tools, like following

xcrun agvtool next-version -all # increment build number
xcrun agvtool new-marketing-version 1.0.0

For more details: https://developer.apple.com/library/archive/qa/qa1827/_index.html

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