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diff --git a/Master/texmf-dist/doc/generic/FAQ-en/html/FAQ-spawnprog.html b/Master/texmf-dist/doc/generic/FAQ-en/html/FAQ-spawnprog.html deleted file mode 100644 index 0d0f1e1ae09..00000000000 --- a/Master/texmf-dist/doc/generic/FAQ-en/html/FAQ-spawnprog.html +++ /dev/null @@ -1,63 +0,0 @@ -<head> -<title>UK TeX FAQ -- question label spawnprog</title> -</head><body> -<h3>Spawning programs from (La)TeX: <code>\</code><code>write18</code></h3> -<p/>The TeX <a href="FAQ-write.html"><code>\</code><code>write</code> primitive instruction</a> is used -to write to different file ‘streams’; TeX refers to each open file by -a number, not by a file name (although most of the time we hide this). -Originally, TeX would write to a file connected to a stream -numbered 0–15. More recently, a special “stream 18” has been -implemented: it is not writing to a file, but rather tells TeX to ask -the operating system to do something. To run a command, we put it as -the argument to <code>\</code><code>write18</code>. So to run the <i>epstopdf</i> -program on a file with name stored as <code>\</code><code>epsfilename</code>, we would -write: -<blockquote> -<pre> -\write18{epstopf \epsfilename} -</pre> -</blockquote><p> -When using something like the <i>epstopdf</i> package, the ‘stream’ -write operation is hidden away and you don’t need to worry about the -exact way it’s done. -<p/>However, there is a security issue. If you download some (La)TeX code from -the Internet, can you be sure that there is not some command in it -(perhaps in a hidden way) to do stuff that might be harmful to your -PC (let’s say: delete everything on the hard disk!)? In the -face of this problem, both MiKTeX and TeX Live have, for some -time, disabled <code>\</code><code>write18</code> by default. To turn the facility on, -both distributions support an additional argument when starting TeX -from the command shell: -<blockquote> -<pre> -(pdf)(la)tex --shell-escape <file> -</pre> -</blockquote><p> -The problem with this is that many people use (La)TeX via a graphical -editor, so to use <code>\</code><code>write18</code> for a file the editor’s settings must -be changed. Of course, the settings need restoring after the file is -processed: you defeat the point of the original protection, that way. -<p/>The latest MiKTeX (version 2.9), and TeX Live (2010 release) get -around this by having a special “limited” version of <code>\</code><code>write18</code> -enabled ‘out of the box’. The idea is to allow only a pre-set list of -commands (for example, BibTeX, <i>epstopdf</i>, TeX itself, -and so on). Those on the list are regarded as safe enough to allow, -whereas anything else (for example deleting files) still needs to be -authorised by the user. This seems to be a good balance: most people -most of the time will not need to worry about <code>\</code><code>write18</code> at all, -but it will be available for things like <i>epstopdf</i>. -<p/>Note that the TeX system may tell you that the mechanism is in use: -<blockquote> -<pre> -This is pdfTeX, Version 3.1415926-1.40.11 (TeX Live 2010) - restricted \write18 enabled. -</pre> -</blockquote><p> - -when it starts. -<dl> -<dt><tt><i>epstopdf.sty</i></tt><dd>Distributed with Heiko Oberdiek’s packages - <a href="http://mirror.ctan.org/macros/latex/contrib/oberdiek.zip">macros/latex/contrib/oberdiek</a> (or <a href="http://mirror.ctan.org/macros/latex/contrib/oberdiek/">browse the directory</a>); <a href="http://mirror.ctan.org/help/Catalogue/entries/oberdiek.html">catalogue entry</a> -</dl> -<p/><p>This question on the Web: <a href="http://www.tex.ac.uk/cgi-bin/texfaq2html?label=spawnprog">http://www.tex.ac.uk/cgi-bin/texfaq2html?label=spawnprog</a> -</body> |