Building

The build option can be invoked either from b or build like shown below

$ apktool b foo.jar.out
# builds foo.jar.out folder into foo.jar.out/dist/foo.jar

$ apktool build foo.jar.out
# builds foo.jar.out folder into foo.jar.out/dist/foo.jar

$ apktool b bar
# builds bar folder into bar/dist/bar.apk

$ apktool b .
# builds current directory into ./dist

$ apktool b bar -o new_bar.apk
# builds bar folder into new_bar.apk

$ apktool b bar.apk
# WRONG: brut.androlib.AndrolibException: brut.directory.PathNotExist: apktool.yml
# Must use folder, not apk/jar file

info

In order to run a rebuilt application, you must resign it. Android documentation can help with this.