# Use output of external command in xifthen

It would like to call the kdb command from Elektra from within LaTeX documents and use its output to write LaTeX conditionals.

Ideally, I would like to have something like:

\documentclass{article}
\usepackage{xifthen}
\usepackage{elektra}

\begin{document}
user/tests/examples is \kdb{user/tests/examples}

\ifthenelse{\kdbistrue{user/tests/examples}}%
{true}%
{false}

\ifthenelse{\kdbisnull{user/tests/examples}}%
{key value is empty}%
{key value is not empty}

\ifthenelse{\kdbispresent{user/tests/examples}}%
{key is present}%
{key is not present}

% should play well with standard xifthen features (like equal):
\ifthenelse{\equal{\kdb{user/tests/examples}}{something}}%
{something}%
{not something}
\end{document}


What I tried so far:

\documentclass{article}
\usepackage{xifthen}

\def \var {\input|"kdb sget user/tests/examples 0"}

\begin{document}

\ifthenelse{\isin{0}{\var}}% does not work
{false}%
{true}

\ifthenelse{\equal{\var}{1}}% does not work
{is 1}%
{is not 1}

\ifthenelse{\isempty{\var}}}% does not work
{empty}%
{not empty}
\end{document}


Unfortunately I get "undefined control sequence" errors, except for the conditionals which use isin and isempty, which always return false.