Build multiarch containers.

arch.txt

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+aarch64
+# aarch64_be
+# alpha
+arm
+# armeb
+# cris
+# hppa
+i386
+# m68k
+# microblaze
+# microblazeel
+# mips
+# mips64
+# mips64el
+# mipsel
+# mipsn32
+# mipsn32el
+# nios2
+# or1k
+# ppc
+# ppc64
+# ppc64abi32
+ppc64le
+# riscv32
+# riscv64
+s390x
+# sh4
+# sh4eb
+# sparc
+# sparc32plus
+# sparc64
+# tilegx
+x86_64
+# xtensa
+# xtensaeb

build.sh

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+#!/usr/bin/env sh
+
+platforms() {
+    local plat="$(grep '^[^#].*' < arch.txt)"
+    local arch_count="$(echo "$plat" | wc -l)"
+    echo "$plat" | tr '\n' ',' | cut -d, -f1-$arch_count
+}
+
+create() {
+    docker buildx create --use
+}
+
+build() {
+    local tagname="$1"
+    docker pull 'alpine:latest'
+    docker buildx build --push --tag="$tagname" --platform="$(platforms)" .
+}
+
+"$@"