pyb

#!/bin/bash

# fail on errors and intermediate non-zero exit-codes in pipes
# also called bash safe-mode
set -eo pipefail

# set default variables
# can be overwritten by setting the environment variable
version=${version:-3.7.2}
cache="${cache:-${PWD}}"
prefix="${prefix:-${PWD}/target}"

_build() {
    mkdir -p "$cache" "$prefix"

    cores_num=$(nproc --all)

    # download, extract and verfiy signature in one-step
    curl --silent --fail "https://www.python.org/ftp/python/$version/Python-$version.tar.xz"\
        | tee >(tar --extract --xz -C "$cache")\
        | gpg --verify <(curl --fail "https://www.python.org/ftp/python/$version/Python-$version.tar.xz.asc") -

    # push directory on stack
    pushd "${cache}/Python-$version"
    ./configure --prefix=$prefix --enable-optimizations

    make -j $cores_num
    make -j $cores_num install

    # pop directory from stack
    popd
}

_help() {
    cat<<EOF
version=$version cache=$cache prefix=$prefix $0 build

    version: python version to build
    cache: directory for build cache
    prefix: package prefix directory

    Default values are shown, setting variables is optional
EOF
}

case "$1" in
    "help"|"-h"|"--help")
        _help
        exit 0
        ;;
    "build")
        # fail on unset variables
        set -u
        _build
        ;;
    ""|"*")
        _help
        exit 1
        ;;
esac