Add aliases of switch PHP versions on Mac OS

switch_php_versions.sh

# 1. Need to install PHP with `brew install ...`
# 2. Need to install grep `brew install grep`
# 3. Paste it in your `~/.zshrc` 
# Updated from https://localheinz.com/blog/2020/05/05/switching-between-php-versions-when-using-homebrew/

# determine versions of PHP installed with HomeBrew
installedPhpVersions=($(brew ls --versions | ggrep -E 'php(@.*)?\s' | ggrep -oP '(?<=\s)\d\.\d' | uniq | sort))

# create alias for every version of PHP installed with HomeBrew
for phpVersion in ${installedPhpVersions[*]}; do
    value="{"

    for otherPhpVersion in ${installedPhpVersions[*]}; do
        if [ "${otherPhpVersion}" = "${phpVersion}" ]; then
            continue
        fi

        # unlink other PHP version
        value="${value} brew unlink php@${otherPhpVersion};"
    done

    # link desired PHP version
    value="${value} brew link php@${phpVersion} --force --overwrite; } &> /dev/null && echo '${phpVersion}' > ~/.php_version && source ~/.zshrc && php -v"

    alias "${phpVersion}"="${value}"
done

export PHP_VERSION=$(<~/.php_version)
export PATH="/opt/homebrew/opt/php@$PHP_VERSION/bin:$PATH"
export PATH="/opt/homebrew/opt/php@$PHP_VERSION/sbin:$PATH"