Must specify PROTOC if not bootstrapping from the distribution artifact

./compile.sh
  Building Bazel from scratch
ERROR: Must specify PROTOC if not bootstrapping from the distribution artifact

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NOTE: This failure is likely occuring if you are trying to bootstrap bazel from
a developer checkout. Those checkouts do not include the generated output of
the protoc compiler (as we prefer not to version generated files).

* To build a developer version of bazel, do

    bazel build //src:bazel

* To bootstrap your first bazel binary, please download a dist archive from our
  release page at https://github.com/bazelbuild/bazel/releases and run
  compile.sh on the unpacked archive.

The full install instructions to install a release version of bazel can be found
at https://docs.bazel.build/install-compile-source.html
For a rationale, why the bootstrap process is organized in this way, see
https://bazel.build/designs/2016/10/11/distribution-artifact.html
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sudo apt install protobuf-compiler