cereda

\documentclass{article}
\usepackage{filecontents}
\usepackage{graphicx}

\newcommand{\generateimage}[2]{%
\immediate\write18{convert.cmd #1 > #2}}

\begin{document}

\begin{filecontents*}{myfigure.txt}

cereda

rem for Windows
php convert.php %1
-----------------------
# for Linux
php convert.php $1

cereda

<?php

// Note: this script was written just for testing
// purposes. It has no error checking and other
// controls. DO NOT RUN THIS COMMAND WITHOUT
// REDIRECTING THE OUTPUT TO A FILE, e.g.,
// convert.php mystring.txt > out.png

// open the file
$handler = fopen($argv[1], 'r');

cereda

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