writing inheaderin latex code example

Example: how to add footer only on first page latex

\documentclass{report}
\usepackage{atbegshi}
\usepackage{fancyhdr}
\usepackage{lipsum} % just for the example

\fancyhf{}
\pagestyle{fancy}

\AtBeginDocument{%
  \rfoot{Alim, from Unknown City}%
  \AtBeginShipoutNext{%
    \rfoot{}%
  }%
}

\begin{document}
\lipsum[1-20]
\end{document}