Anyone know how to use $CIRCLE_BUILD_NUM across different jobs in CircleCI?
This is the approach I came up with.  It's kinda ugly, but it does work:

- run:
    name: Create unique build identifier
    command: |
        GIT_SHA=$( git rev-parse --short HEAD )
        echo "export GIT_SHA=${GIT_SHA}" &gt;&gt; "${BASH_ENV}"

        # the always-increasing counter, based on CIRCLE_BUILD_NUM
        BUILD_COUNTER="${CIRCLE_BUILD_NUM}"
        echo "export BUILD_COUNTER=${BUILD_COUNTER}" &gt;&gt; "${BASH_ENV}"

        # the build identifier, which includes the short git sha
        BUILD_NUMBER="CIRC${BUILD_COUNTER}-${GIT_SHA}"
        echo "export BUILD_NUMBER=${BUILD_NUMBER}" &gt;&gt; "${BASH_ENV}"

        # output build id and counter
        echo -e "\nbuild counter: ${BUILD_COUNTER}; build id: ${BUILD_NUMBER}\n"


Then ${BUILD_NUMBER} is available as an environment variable in other steps.