usage: ./build.sh [-c] [-nd] [-r ALL|level.name.build[:step]] [-h] [-t]
        -c                     Clean $PREFIX before processing build scripts.
        -i level.name.build    Insert link to pkg.build for the specified build script.
                               All consecutive scripts with higher build levels will
                               be renamed automatically.
        -nd                    Don't rm(1) and re-download tarballs when not required.
        -h                     Show this screen.
        -pt                    Enable pedantic mode. In addition to the warnings emitted
                               whenever a potentially dangerous operation is invoked by
                               the build scripts, manual confirmation will be required.
                               This currently only includes rm_if_exists().
        -r ALL|level.name.build[:step]
                               Restart all or the specified build script(s) completely
                               or at the optionally specified build step. Currently defined
                               build steps are: fetch extract build_dir patch configure clean
                               build install configure1 configure2 build1 build2 install1 install2.
        -t[.gz|.bz2|.xz]       Produce binary distribution and source tarballs containing $PREFIX
                               sans $WORKDIR and $PREFIX/src/midipix_build and $WORKDIR sans top-
                               level regular files at the end of a build with zero failures. The
                               tarballs will be compressed with either gzip, bzip2, or xz and signed
                               with GPG; the default compression is xz.
        -x                     Set the xtrace sh(1)ell option for debugging purposes.
        -X                     Set the xtrace sh(1)ell option and compile a tarball containing
                               build.log and $PKG_SUBDIR. Use this option if something goes
                               wrong and provide an URL to the tarball in <irc://irc.freenode.net/midipix>.

        Packages that are built by pkg.build will apply local patches in $WORKDIR
        named ${PKG_SUBDIR}.local.patch.

        Examples:
        ./build.sh -r ALL
        Forcibly restart the entire build.

        ./build.sh -r 301.coreutils.build
        Completely restart the coreutils build.

        ./build.sh -r 301.coreutils.build:configure,build,install
        Restart the configure, build, and install steps of the coreutils build script.

        ./build.sh -r 205.psxscl.build GITROOT_HEAD=... PKG_PSXSCL_CFLAGS_CONFIGURE_EXTRA=-DPSX_INTERNAL_STRACE
        Build psxscl from the internal repository with strace enabled.

        ./build.sh -c -r ALL GITROOT_HEAD=...
        Clean $PREFIX and forcibly rebuild everything.

This script has been tested on the following platforms:
Arch Linux 2016.02.01 (x86_64)
CentOS v7.2.1511 (Core) (x86_64)
Debian GNU/Linux v8.5 (stable) (jessie) (x86_64)
Exherbo Linux (x86_64-pc-linux-musl) (x86_64)
openSUSE 20150612 (Tumbleweed) (x86_64)