Dockerfile

FROM alpine:3.4

ARG FOO
ADD test.sh .
RUN ./test.sh

shell.md

$ docker build --build-arg FOO=BAR -t test .
Sending build context to Docker daemon 3.072 kB
Step 1 : FROM alpine:3.4
 ---> 4e38e38c8ce0
Step 2 : ARG FOO
 ---> Running in c5c23c421a6c
 ---> b251b85eefb1
Removing intermediate container c5c23c421a6c
Step 3 : ADD test.sh .
 ---> 86b3a69480a6
Removing intermediate container 7951d7e2806a
Step 4 : RUN ./test.sh
 ---> Running in 9540d627df3f
BAR
 ---> 028dce4ef40a
Removing intermediate container 9540d627df3f
Successfully built 028dce4ef40a

test.sh

#!/bin/sh
echo $FOO