AWS DevOps Engineer Professional DOP-C01 – Question488

When building a Docker image, you are searching through a persistent data volume's logs to provide parameters for the next build. You execute the following command. Which of the operations will cause a failure of the Docker RUNcommand? RUN cat ./data/log/*.error | grep service_status | grep ERROR

A. the first grep command
B. any one of them
C. the second grep command
D. the cat command

Correct Answer: C

Explanation:

Explanation:
Some RUN commands depend on the ability to pipe the output of one command into another, using the pipe character (|), as in the following example:
RUN wget -O – https://some.site | wc -l > /number
Docker executes these commands using the /bin/sh -c interpreter, which only evaluates the exit code of the last operation in the pipe to determine success. In the example above this build step succeeds and produces a new image so long as the wc -lcommand succeeds, even if the wget command fails.
Reference:
https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-…