
# Select package manager for the OS (sets the $PKG_MANAGER* variables)
if [ -z "$PKG_MANAGER" ]; then
  if [ -f /etc/os-release ] ; then
    . /etc/os-release
  fi
  
  if [ "${NAME%.*}" = 'FreeBSD' ]; then
    PKG_MANAGER='pkg'
    PKG_MANAGER_INSTALL="${PKG_MANAGER} install -y"
    PKG_MANAGER_REMOVE="${PKG_MANAGER} delete -y"
    PKG_MANAGER_UPGRADE="${PKG_MANAGER} install -y"
  elif [ -f /etc/fedora-release -o -f /etc/redhat-release -o -f /etc/amazon-linux-release -o -f /etc/system-release ]; then
    PKG_MANAGER='dnf'
    if [ -f /etc/redhat-release -a "${VERSION_ID%.*}" -le 7 ]; then
      PKG_MANAGER='yum'
    elif [ -f /etc/system-release ]; then
      PKG_MANAGER='yum'
    fi
    PKG_MANAGER_INSTALL="${PKG_MANAGER} install -y"
    PKG_MANAGER_REMOVE="${PKG_MANAGER} remove -y"
    PKG_MANAGER_UPGRADE="${PKG_MANAGER} upgrade -y"
  elif [ -f /etc/debian_version ]; then
    PKG_MANAGER='apt-get'
    PKG_MANAGER_INSTALL="${PKG_MANAGER} -o 'Dpkg::Options::=--force-confdef' -o 'Dpkg::Options::=--force-confold' install -y"
    PKG_MANAGER_REMOVE="${PKG_MANAGER} remove -y"
    PKG_MANAGER_UPGRADE="${PKG_MANAGER} -o 'Dpkg::Options::=--force-confdef' -o 'Dpkg::Options::=--force-confold' -o APT::Get::Upgrade-Allow-New='true' upgrade -y"
  elif [ -f /etc/arch-release ]; then
    PKG_MANAGER='pacman'
    PKG_MANAGER_INSTALL="${PKG_MANAGER} --noconfirm -S"
    PKG_MANAGER_REMOVE="${PKG_MANAGER} --noconfirm -R"
    PKG_MANAGER_UPGRADE="${PKG_MANAGER} --noconfirm -S"
  elif [ x$ID = xopensuse-tumbleweed -o x$ID = xsles ]; then
    PKG_MANAGER='zypper'
    PKG_MANAGER_INSTALL="${PKG_MANAGER} --non-interactive install --auto-agree-with-licenses"
    PKG_MANAGER_REMOVE="${PKG_MANAGER} --non-interactive remove"
    PKG_MANAGER_UPGRADE="${PKG_MANAGER} --non-interactive update"
  fi
fi

