% Switches.
\newif\ifPhoto % Show photo.
\newif\ifExtra % Show extra content.
\newif\ifEn    % English language.
\newif\ifRu    % Russian language.
\newcommand{\En}[1]{\ifEn#1\fi} % Print if English language.
\newcommand{\Ru}[1]{\ifRu#1\fi} % Print if Russian language.

% Read env variables.
\def\envTrue{true}   % True.
\def\envFalse{false} % False.
\def\envEn{en}       % English literal.
\def\envRu{ru}       % Russian literal.
\def\envEmpty{}      % Empty env value.
\GetEnv[\envPhoto]{DOCUMENT_PHOTO} % Read photo shell variable.
\GetEnv[\envExtra]{DOCUMENT_EXTRA} % Read extra shell variable.
\GetEnv[\envLang]{DOCUMENT_LANG}   % Read language shell variable.
\ifdefequal{\envPhoto}{\envTrue}{\Phototrue}{\Photofalse} % Show photo.
\ifdefequal{\envExtra}{\envTrue}{\Extratrue}{\Extrafalse} % Show extra content.
\ifdefequal{\envLang}{\envEn}{\Entrue}{}                  % Use English.
\ifdefequal{\envLang}{\envRu}{\Rutrue}{}                  % Use Russian.
\ifdefequal{\envLang}{\envEmpty}{\Entrue}{}               % Use English by default.