[latex3-commits] [git/LaTeX3-latex3-latex2e] develop: remove description of dvips backtick mechanism which has not worked for years (9bb8f12d)

[David Carlisle]

Repository : https://github.com/latex3/latex2e
On branch  : develop
Link       : https://github.com/latex3/latex2e/commit/9bb8f12d5c97a3eccf700c8c1f043dda0bf5cf56

>---------------------------------------------------------------

commit 9bb8f12d5c97a3eccf700c8c1f043dda0bf5cf56
Author: David Carlisle <d.p.carlisle at gmail.com>
Date:   Fri Mar 5 19:33:14 2021 +0000

    remove description of dvips backtick mechanism which has not worked for years


>---------------------------------------------------------------

9bb8f12d5c97a3eccf700c8c1f043dda0bf5cf56
 required/graphics/changes.txt  |  8 ++++++++
 required/graphics/grfguide.tex | 30 +++++++-----------------------
 2 files changed, 15 insertions(+), 23 deletions(-)

diff --git a/required/graphics/changes.txt b/required/graphics/changes.txt
index 6f608f2a..25ad5fdd 100644
--- a/required/graphics/changes.txt
+++ b/required/graphics/changes.txt
@@ -4,6 +4,14 @@ completeness or accuracy and it contains some references to files that
 are not part of the distribution.
 =======================================================================
 
+2021-03-05  David Carlisle  <David.Carlisle at latex-project.org>
+
+	* grfguide.tex: Remove the example of calling zcat via the
+	backtick special in dvips which has not worked for many years
+	for security reasons.  dvips directly supports zip
+	uncompression, and does not allow arbitrary shell commands to
+	be executed via \special{`command..}
+
 2021-03-03  Phelype Oleinik  <phelype.oleinik at latex-project.org>
 
 	* graphics.dtx: Avoid warning when loading a file using a generic rule (gh/516).
diff --git a/required/graphics/grfguide.tex b/required/graphics/grfguide.tex
index 06a52056..3b679ea3 100644
--- a/required/graphics/grfguide.tex
+++ b/required/graphics/grfguide.tex
@@ -62,7 +62,7 @@ stroke
 \begin{document}
 \title{Packages in the `graphics' bundle}
 \author{D. P. Carlisle \and The \LaTeX\ Project}
-\date{2020-08-21}
+\date{2021-03-05}
 
 \maketitle
 
@@ -766,28 +766,12 @@ This would declare a default rule, such that all unknown extensions
 would be treated as EPS files, and the graphic file would be read for
 a BoundingBox comment.
 
-\emph{command} is usually empty, but if non empty it is used in place
-of the filename in the |\special|. Within this argument, |#1| may be
-used to denote the filename. Thus using the dvips driver, one may
-use\\
-|\DeclareGraphicsRule{.ps.gz}{eps}{.ps.bb}{`zcat #1}|\\
-the final argument causes dvips to use the |zcat| command to unzip the
-file before inserting it into the PostScript output.
-
-Note that \LaTeX\ will find the graphics file by searching along
-TEXINPUTS (and possibly other places, as specified with
-|\graphicspath|) however it may be that the command you specify
-in this argument can not find such files unless they are in the
-current directory. On some systems it may be possible to modify
-the command so that it will find any files that \LaTeX\ can find.
-For example on newer web2c \TeX\ releases on unix, one may modify the
-above command so that the last argument is:\\
-|{`zcat `kpsewhich -n latex tex #1`}|\\
-which incantation causes the |kpsewhich| program to find the
-file, by searching along \LaTeX's path, and then pass the full path
-name to the |zcat| program so that it can uncompress the file.
-Any such uses are very system dependent, and would best be placed in
-a |graphics.cfg| file, thus keeping the document itself portable.
+\emph{command} is usually empty, but if non empty it may hold \TeX{} code
+to modify the name of the file as passed to the back end file inclusion
+commands. Within this argument, |#1| may be
+used to denote the original filename. Very early releases of the |dvips| code
+used this mechanism to support compressed EPS files, however for some years
+dvips has directly supported uncompression.
 
 \subsection{Global setting of keys}