A simple box with rounded edges, and with a title, to show command-lines

latex_command-line_box.tex

\usepackage[table, dvipsnames]{xcolor}
\usepackage{changepage}
\usepackage[skins]{tcolorbox}

\newenvironment{coloredterminal}{
    \begin{adjustwidth}{10mm}{}
    \begin{tcolorbox}[colback=gray!10, boxrule=1pt, title=Terminal, fonttitle=\footnotesize]
}{
    \end{tcolorbox}
    \end{adjustwidth}
}

\newcommand{\terminal}[1]{
    \begin{coloredterminal}
    \ttfamily\footnotesize
    #1
    \end{coloredterminal}
}

\begin{document}

% just an example with multiple command-lines.
\terminal{
    sudo apt update \\
    sudo apt upgrade
}

\end{document}