dockerfile - Error while running postgres on ubuntubase docker -

i'm practicing examples provided in book docker in practice chapter 3. below dockerfile mentioned run docker postgres.

from ubuntu:14.04 run apt-get update \    && debian_frontend=noninteractive  apt-get install -y \    postgresql \    && apt-get clean \    && rm -rf /var/lib/apt/lists/* workdir /opt copy db /opt/db run service postgresql start && \    cat db/schema.sql | psql && \    service postgresql stop 

but copy in step 4 gives me below error.

 $ sudo docker build -t db .  sending build context docker daemon  2.048kb  step 1/4 : ubuntu:14.04  ---> c69811d4e993  step 2/4 : run apt-get update     && debian_frontend=noninteractive    apt-get install -y     postgresql     && apt-get clean     && rm -rf   /var/lib/apt/lists/*  ---> using cache  ---> 2ac4ff885d29  step 3/4 : copy db /opt/db  copy failed: stat /var/lib/docker/tmp/docker-builder554911929/db: no such file or directory 

when commented copy command, i'm getting different error.

 step 4/4 : run service postgresql start &&     cat db/schema.sql | psql &&     service postgresql stop  ---> running in 79e47b45c41a * starting postgresql 9.3 database server  ...done.  cat: db/schema.sql: no such file or directory  psql: fatal:  role "root" not exist 

copy db /opt/db supposed copy db current context (the folder executing docker build from)

so make sure said current folder does include db folder.