--- unixtoolbox.xhtml   28 Jan 2009 00:10:02 -0000   1.30
+++ unixtoolbox.xhtml   21 May 2009 11:09:46 -0000
@@ -8,10 +8,10 @@
   <title>Unix Toolbox</title>
   <link rel="icon" href="data:image/x-icon;base64,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" />
   <meta name="author" content="Colin Barschel c@cb.vu" />
-  <meta name="copyright" content="Copyright (c) 2007-2008 Colin Barschel. Some rights reserved under Creative Commons [Attribution - Share Alike]" />
+  <meta name="copyright" content="Copyright (c) 2007-2009 Colin Barschel. Some rights reserved under Creative Commons [Attribution - Share Alike]" />
   <meta name="description" content="A collection of Unix/Linux/BSD commands and tasks which are useful for IT work or for advanced users, a compact and practical reference." />
   <meta name="abstract" content="Unix Toolbox a compact and practical reference for sysadmins and advanced users." />
-  <meta name="subject" content="Unix Toolbox revision 13.4" />
+  <meta name="subject" content="Unix Toolbox revision 14" />
   <meta name="keywords" content="Unix Toolbox, Unix tools, Unix, FreeBSD, Linux, commands list, sysadmin, practical guide, advanced reference, common Linux tasks, syntax reminder, howtos, ssh tunnels, rsync, ssl certificates" />
   <style type="text/css" >
 /* basic CSS common to all media */
@@ -147,10 +147,11 @@
     }
     pre {
         font-size: 90%;
-        margin: 0.4em 0;
+        margin: 0.3em 0 0.3em 0;
         padding: 0.2em 0 0.2em 0.4em;
         text-align: left;
-        line-height: 117%
+        line-height: 117%;
+        letter-spacing:-0.03em
     }
     a {
    text-decoration: none;
@@ -232,7 +233,7 @@
 }
 @page {
     size: A4 portrait;
-    margin: 16mm 14mm 14mm 12mm;
+    margin: 15mm 12mm 14mm 12mm;
     padding: 0mm 0 5mm 0;
     @footnotes {
    border-top: solid #000040 thin;
@@ -402,10 +403,10 @@
 This document is a collection of Unix/Linux/BSD commands and tasks which are useful for IT work or for advanced users. This is a practical guide with concise explanations, however the reader is supposed to know what s/he is doing.<br /><br />
 </div>
 <div class="footerfirst">
-Unix Toolbox revision 13.4<br />
+Unix Toolbox revision 14<br />
 The latest version of this document can be found at <a href="http://cb.vu/unixtoolbox.xhtml">http://cb.vu/unixtoolbox.xhtml</a>. Replace .xhtml on the link with <a href="http://cb.vu/unixtoolbox.pdf">.pdf</a> for the PDF version and with <a href="http://cb.vu/unixtoolbox.book.pdf">.book.pdf</a> for the booklet version. On a duplex printer the booklet will create a small book ready to bind. <span class="web">This XHTML page can be converted into a nice PDF document with a CSS3 compliant application (see the <a class="xref" href="#bourneexample">script example</a>).</span> See also the <a href="http://cb.vu/unixtoolbox">about page</a>.<br />
 Error reports and comments are most welcome - <a href="mailto:c\at\cb.vu">c@cb.vu</a> Colin Barschel.
-<p class="copyright">&#169; <a href="mailto:c_at_cb.vu">Colin Barschel</a> 2007-2008. <a rel="license" href="http://creativecommons.org/licenses/by-sa/3.0/">Some rights reserved under Creative Commons</a>.
+<p class="copyright">&#169; <a href="mailto:c_at_cb.vu">Colin Barschel</a> 2007-2009. <a rel="license" href="http://creativecommons.org/licenses/by-sa/3.0/">Some rights reserved under Creative Commons</a>.
 </p>
 </div> 
 <!-- The table of content is displayed as a fixed vertical right menu
@@ -1584,6 +1585,7 @@
 SSH tunneling allows to forward or reverse forward a port over the SSH connection, thus securing the traffic and accessing ports which would otherwise be blocked. This only works with TCP. The general nomenclature for forward and reverse is (see also <a href="#sshnat">ssh and NAT example</a>):
 <pre># ssh -L localport:desthost:destport user@gate  <span class="cmt"># desthost as seen from the gate</span>
 # ssh -R destport:desthost:localport user@gate  <span class="cmt"># forwards your localport to destination</span>
+    <span class="cmt"># desthost:localport as seen from the client initiating the tunnel</span>
 # ssh -X user@gate   <span class="cmt"># To force X forwarding</span>
 </pre>
 This will connect to gate and forward the local port to the host desthost:destport. Note desthost is the destination host <i>as seen by the gate</i>, so if the connection is to the gate, then desthost is localhost. More than one port forward is possible.
@@ -1651,6 +1653,14 @@
 # scp -P 5678 myfile localhost:/tmp/            <span class="cmt"># or copy a file directly using the tunnel</span>
 # rsync -e 'ssh -p 5678' myfile localhost:/tmp/ <span class="cmt"># or rsync a file directly to the server</span>
 </pre>
+<h3>Autoconnect and keep alive script</h3>
+I use variations of the following script to keep a machine reacheable over a reverse ssh tunnel. The connection is automatically rebuilt if closed. You can add multiple <code>-L</code> or <code>-R</code> tunnels on one line.
+<pre>#!/bin/sh
+COMMAND="ssh -N -f -g -R 3022:localhost:22 colin@cb.vu"
+pgrep -f -x "$COMMAND" &gt; /dev/null 2&gt;&amp;1 || $COMMAND
+exit 0
+</pre>
+<pre>1 * * * * colin /home/colin/port_forward.sh     <span class="cmt"># crontab entry (here hourly)</span></pre>
 </div>
 
 <div id="vpn"><h1><a>VPN with SSH</a></h1>
@@ -1732,14 +1742,15 @@
 <div id="rsync"><h1><a>RSYNC</a></h1>
 Rsync can almost completely replace cp and scp, furthermore interrupted transfers are efficiently restarted. A trailing slash (and the absence thereof) has different meanings, the man page is good... Here some examples:<br />
 Copy the directories with full content:
-<pre># rsync -a /home/colin/ /backup/colin/
+<pre># rsync -a /home/colin/ /backup/colin/                <span class="cmt"># "archive" mode. e.g keep the same</span>
 # rsync -a /var/ /var_bak/
 # rsync -aR --delete-during /home/user/ /backup/      <span class="cmt"># use relative (see below)</span>
 </pre>
 Same as before but over the network and with compression. Rsync uses SSH for the transport per default and will use the ssh key if they are set. Use ":" as with SCP. A typical remote copy:
-<pre># rsync -axSRzv /home/user/ user@server:/backup/user/</pre>
+<pre># rsync -axSRzv /home/user/ user@server:/backup/user/ <span class="cmt"># Copy to remote</span>
+# rsync -a 'user@server:My\ Documents' My\ Documents  <span class="cmt"># Quote AND escape spaces for the remote shell</span></pre>
 Exclude any directory tmp within /home/user/ and keep the relative folders hierarchy, that is the remote directory will have the structure /backup/home/user/. This is typically used for backups.
-<pre># rsync -azR --exclude /tmp/ /home/user/ user@server:/backup/</pre>
+<pre># rsync -azR --exclude=tmp/ /home/user/ user@server:/backup/</pre>
 
 Use port 20022 for the ssh connection:
 <pre># rsync -az -e 'ssh -p 20022' /home/colin/ user@server:/backup/colin/</pre>
@@ -2542,6 +2553,10 @@
 </div>
 
 <div id="software"><h1><a>Install Software</a></h1>
+Usually the package manager uses the proxy variable for http/ftp requests. In .bashrc:
+<pre>export http_proxy=http://proxy_server:3128
+export ftp_proxy=http://proxy_server:3128
+</pre>
 <h2 id="softwarelist">List installed packages</h2>
 <pre># rpm -qa                            <span class="cmt"># List installed packages (RH, SuSE, RPM based)</span>
 # dpkg -l                            <span class="cmt"># Debian, Ubuntu</span>
@@ -2628,12 +2643,12 @@
  -dMaxStripSize=8192 -sOutputFile=unixtoolbox_%d.jpg unixtoolbox.pdf
 # convert unixtoolbox.pdf unixtoolbox-%03d.png
 # convert *.jpeg images.pdf          <span class="cmt"># Create a simple PDF with all pictures</span>
+# convert image000* -resample 120x120 -compress JPEG -quality 80 images.pdf
 </pre>
 Ghostscript can also concatenate multiple pdf files into a single one. This only works well if the PDF files are "well behaved".
 <pre># gs -q -sPAPERSIZE=a4 -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=all.pdf \
 file1.pdf file2.pdf ...              <span class="cmt"># On Windows use '#' instead of '='</span>
 </pre>
-
 <h2>Convert video</h2>
 Compress the Canon digicam video with an mpeg4 codec and repair the crappy sound.
 <pre># mencoder -o videoout.avi -oac mp3lame -ovc lavc -srate 11025 \
@@ -2668,6 +2683,8 @@
 </pre>
 Some devices are not postscript and will print garbage when fed with a pdf file. This might be solved with:
 <pre># gs -dSAFER -dNOPAUSE -sDEVICE=deskjet -sOutputFile=\|lpr file.pdf</pre>
+Print to a PDF file even if the application does not support it. Use <code>gs</code> on the print command instead of <code>lpr</code>.
+<pre># gs -q -sPAPERSIZE=a4 -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=/path/file.pdf</pre>
 </div>
 
 <div id="databases"><h1><a>Databases</a></h1>
@@ -3191,7 +3208,7 @@
 <!-- <div class="pb" /> -->
 
 <div class="footerlast">
-This document: "Unix Toolbox revision 13.4" is licensed under a <a rel="nofollow" href="http://creativecommons.org/licenses/by-sa/3.0/">Creative Commons Licence [Attribution - Share Alike]</a>. &#169; <a href="mailto:c_at_cb.vu">Colin Barschel</a> 2007-2008. Some rights reserved.
+This document: "Unix Toolbox revision 14" is licensed under a <a rel="nofollow" href="http://creativecommons.org/licenses/by-sa/3.0/">Creative Commons Licence [Attribution - Share Alike]</a>. &#169; <a href="mailto:c_at_cb.vu">Colin Barschel</a> 2007-2009. Some rights reserved.
 </div>
 
 </body>

Success, CVS operation completed