usage: ./build.sh [-a nt32|nt64]  [-b debug|release]   [-C dir[,..]]  [-D kind[,..]]
                  [-F ipv4|ipv6|offline] [-h|--help|  [-p jobs]  [-P]  [-r ALL|LAST]
                  [-r [*[*[*]]]name[,..][:[^|<|<=|>|>=]step,..]]  [-R] [-v[v[v[v]]]]
                  [--as-needed] [--debug-minipix] [--dump-on-abort]  [--reset-state]
                  [--roar]     [[=]<group>|<variable name>=<variable override>[ ..]]

        -a nt32|nt64      Selects 32-bit or 64-bit architecture; defaults to nt64.
        -b debug|release  Selects debug or release build kind; defaults to debug.
        -C dir[,..]       Clean build directory (build,) ${PREFIX} before processing build
                          scripts (prefix,) source directory (src,) and/or destination
                          directory (dest) after successful package builds.
        -D kind[,..]      Produce minimal midipix distribution directory (minipix,) RPM
                          binary packages (rpm,) and/or deployable distribution ZIP
                          archive (zipdist.) zipdist implies minipix.
        -F ipv4|ipv6|offline
                          Force IPv4 (ipv4) or IPv6 (ipv6) when downloading package
                          archives and/or Git repositories or don't download either at all
                          (offline.)
        -h|--help         Show short/full help screen, respectively.
        -p jobs           Enables parallelisation at group-level, whenever applicable.
        -P                The maximum count of jobs defaults to the number of logical
                          processors on the host system divided by two (2.)

                          If -R is not specified and at least one (1) package fails to
                          build, all remaining package builds will be forcibly aborted.

        -r ALL|LAST       Restart all packages or the last failed package and resume
                          build, resp.
        -r [*[*[*]]]name[,..][:ALL|LAST|[^|<|<=|>|>=]step,..]
                          Restart the specified comma-separated package(s) w/ inhibition
                          of package build step state resetting completely (`ALL',) starting
                          at the resp. last successfully executed build steps (`LAST',) or the
                          specified comma-separated list of build steps, optionally subject
                          concerning package name(s) and/or build step(s) to the below modifiers:

                          Prepend name w/ `*' to automatically include dependencies, `**'
                          to forcibly rebuild all dependencies, and `***` to forcibly
                          rebuild all packages that depend on the specified package(s).

                          Prepend step w/ `^' to filter build steps with, `<' or `<='
                          to constrain build steps to below or below or equal with, resp.,
                          `>' or `>=' to constrain build steps to above or above or equal
                          with, resp.

                          Currently defined build steps are:
                          fetch_clean, fetch_download, fetch_extract, configure_clean,
                          configure_patch_pre, configure_autotools, configure_patch,
                          configure, build_clean, build, install_clean, install_subdirs,
                          install_make, install_files, install_libs, install, install_rpm,
                          and clean.

                          Additionally, the following virtual steps are provided:
                          @fetch, @configure, @build, @install, @clean, and finish.

        -R                Ignore build failures, skip printing package logs, and continue
                          building (relaxed mode.)
        -v[v[v[v]]]       Be verbose; -vv: always print package logs; -vvv: set xtrace
                          during package builds; -vvvv: logs fileops.
        --as-needed       Don't build unless the midipix_build repository has received
                          new commits.
        --debug-minipix   Don't strip(1) minipix binaries to facilitate debugging minipix.
        --dump-on-abort   Produce package environment dump files on build failure to be
                          used in conjuction with pkg_shell.sh script (excludes -R.)
        --reset-state     Reset package build step state on exit.
        <group>[ ..]      One of: dev_packages, dist, host_deps, host_deps_rpm,
                          host_toolchain, host_tools, minipix, native_packages,
                          native_runtime, native_toolchain, native_tools.

                          Prepend w/ `=' to inhibit group-group dependency expansion.

        <variable name>=<variable override>[ ..]
                          Override build or package variable.