--- unixtoolbox.xhtml   8 Aug 2008 17:22:45 -0000   1.26
+++ unixtoolbox.xhtml   7 Nov 2008 12:44:17 -0000   1.27
@@ -11,7 +11,7 @@
   <meta name="copyright" content="Copyright (c) 2007-2008 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 13.1" />
+  <meta name="subject" content="Unix Toolbox revision 13.2" />
   <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 */
@@ -402,7 +402,7 @@
 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 13.1<br />
+Unix Toolbox revision 13.2<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>.
@@ -460,7 +460,7 @@
 <div class="pb" />
  <!-- <div class="main"> Every chapter is inside a div block for easy XML parsing -->
 <div id="sysinfo"><h1><a>System</a></h1>
-<p class="xrefp"><a class="xrefp" href="#hardwareinfo">Hardware</a> | <a class="xrefp" href="#loadstats">Statistics</a> | <a class="xrefp" href="#users">Users</a> | <a class="xrefp" href="#limits">Limits</a> | <a class="xrefp" href="#runlevels">Runlevels</a> | <a class="xrefp" href="#resetpasswd">root password</a> | <a class="xrefp" href="#compilekernel">Compile kernel</a></p>
+<p class="xrefp"><a class="xrefp" href="#hardwareinfo">Hardware</a> | <a class="xrefp" href="#loadstats">Statistics</a> | <a class="xrefp" href="#users">Users</a> | <a class="xrefp" href="#limits">Limits</a> | <a class="xrefp" href="#runlevels">Runlevels</a> | <a class="xrefp" href="#resetpasswd">root password</a> | <a class="xrefp" href="#compilekernel">Compile kernel</a> | <a class="xrefp" href="#grub">Repair grub</a></p>
 Running kernel and system information
 <pre># uname -a                           <span class="cmt"># Get the kernel version (and BSD version)</span>
 # lsb_release -a                     <span class="cmt"># Full release info of any LSB distribution</span>
@@ -602,7 +602,7 @@
 <pre># grep default: /etc/inittab                                         
 id:3:initdefault:
 </pre>
-The actual runlevel (the list is shown below) can be changed with <code>init</code>. For example to go from 3 to 5:
+The actual runlevel can be changed with <code>init</code>. For example to go from 3 to 5:
 <pre># init 5                             <span class="cmt"># Enters runlevel 5</span></pre>
 <ul style="list-style-type:none; page-break-inside:avoid;">
   <li>0 &#160; &#160; &#160; Shutdown and halt</li>
@@ -720,13 +720,23 @@
 # reboot
 # mergemaster -p                     <span class="cmt"># Compares only files known to be essential</span>
 # make installworld
-# mergemaster -i -U                  <span class="cmt"># Update all configuration and other files</span>
+# mergemaster -i -U                  <span class="cmt"># Update all configurations and other files</span>
 # reboot
 </pre>
-For small changes in the source you can use NO_CLEAN=yes to avoid rebuilding the whole tree. But use with care.
+For small changes in the source you can use NO_CLEAN=yes to avoid rebuilding the whole tree.
 <pre># make buildworld NO_CLEAN=yes       <span class="cmt"># Don't delete the old objects</span>
 # make buildkernel KERNCONF=MYKERNEL NO_CLEAN=yes
 </pre>
+
+<h2 id="grub">Repair grub</h2>
+So you broke grub? Boot from a live cd, [find your linux partition under <code>/dev</code> and use <code>fdisk</code> to find the linux partion] mount the linux partition, add /proc and /dev and use <code>grub-install /dev/xyz</code>. Suppose linux lies on <code>/dev/sda6</code>:
+<pre># mount /dev/sda6 /mnt               <span class="cmt"># mount the linux partition on /mnt</span>
+# mount --bind /proc /mnt/proc       <span class="cmt"># mount the proc subsystem into /mnt</span>
+# mount --bind /dev /mnt/dev         <span class="cmt"># mount the devices into /mnt</span>
+# chroot /mnt                        <span class="cmt"># change root to the linux partition</span>
+# grub-install /dev/sda              <span class="cmt"># reinstall grub with your old settings</span>
+</pre>
+
 </div>
 
 <div id="processes"><h1><a>Processes</a></h1>
@@ -2368,8 +2378,8 @@
 <pre># tar -tzf home.tgz             <span class="cmt"># look inside the archive without extracting (list)</span>
 # tar -xf home.tar              <span class="cmt"># extract the archive here (x for extract)</span>
 # tar -xzf home.tgz             <span class="cmt"># same with zip compression</span>
-# tar -xjf home.tgz             <span class="cmt"># same with bzip2 compression</span>
-# tar -xjf home.tgz home/colin/file.txt    <span class="cmt"># Restore a single file</span>
+# tar -xjf home.tbz             <span class="cmt"># same with bzip2 compression</span>
+# tar -xjf home.tbz home/colin/file.txt    <span class="cmt"># Restore a single file</span>
 </pre>
 <h3>More advanced</h3>
 <pre># tar c dir/ | gzip | ssh user@remote 'dd of=dir.tgz' <span class="cmt"># arch dir/ and store remotely.</span>
@@ -2390,8 +2400,8 @@
 The default byte size is 512 (one block). The MBR, where the partition table is located, is on the first block, the first 63 blocks of a disk are empty. Larger byte sizes are faster to copy but require also more memory.
 <h3>Backup and restore</h3>
 <pre># dd if=/dev/hda of=/dev/hdc bs=16065b                <span class="cmt"># Copy disk to disk (same size)</span>
-# dd if=/dev/sda7 of /home/root.img bs=4096 conv=notrunc,noerror <span class="cmt"># Backup /</span>
-# dd if /home/root.img of=/dev/sda7 bs=4096 conv=notrunc,noerror <span class="cmt"># Restore /</span>
+# dd if=/dev/sda7 of=/home/root.img bs=4096 conv=notrunc,noerror <span class="cmt"># Backup /</span>
+# dd if=/home/root.img of=/dev/sda7 bs=4096 conv=notrunc,noerror <span class="cmt"># Restore /</span>
 # dd bs=1M if=/dev/ad4s3e | gzip -c &gt; ad4s3e.gz                  <span class="cmt"># Zip the backup</span>
 # gunzip -dc ad4s3e.gz | dd of=/dev/ad0s3e bs=1M                 <span class="cmt"># Restore the zip</span>
 # dd bs=1M if=/dev/ad4s3e | gzip | ssh eedcoba@fry 'dd of=ad4s3e.gz' <span class="cmt"># also remote</span>
@@ -2436,13 +2446,13 @@
 <h3>Short start example</h3>
 start screen with:
 <pre># screen</pre>
-Within the screen session we can start a long lasting program (like top). Detach the terminal and reattach the same terminal from an other machine (over ssh for example).
+Within the screen session we can start a long lasting program (like top).
 <pre># top</pre>
-Now detach with <strong>Ctrl-a Ctrl-d</strong>. Reattach the terminal with
-<pre># screen -r</pre>
-or better:
+Now detach with <strong>Ctrl-a Ctrl-d</strong>. Reattach the terminal with:
 <pre># screen -R -D</pre>
-Attach here and now. In detail this means: If a session is running, then reattach. If  necessary detach and logout remotely first. If it was not running create it and notify the user.
+In detail this means: If a session is running, then reattach. If  necessary detach and logout remotely first. If it was not running create it and notify the user. Or:
+<pre># screen -x</pre>
+Attach to a running screen in a multi display mode. The console is thus shared among multiple users. Very useful for team work/debug!
 
 <h3>Screen commands (within screen)</h3>
 All screen commands start with <strong>Ctrl-a</strong>.
@@ -2511,6 +2521,7 @@
 # cp -lpR /dir1 /dir2                <span class="cmt"># Same for FreeBSD</span>
 # cp unixtoolbox.xhtml{,.bak}        <span class="cmt"># Short way to copy the file with a new extension</span>
 # mv /dir1 /dir2                     <span class="cmt"># Rename a directory</span>
+# ls -1                              <span class="cmt"># list one file per line</span>
 </pre>
 Check file hashes with openssl. This is a nice alternative to the commands <code>md5sum</code> or <code>sha1sum</code> (FreeBSD uses <code>md5</code> and <code>sha1</code>) which are not always installed.
 <pre># openssl md5 file.tar.gz            <span class="cmt"># Generate an md5 checksum from file</span>
@@ -2590,11 +2601,14 @@
 Without the -f option, iconv will use the local char-set, which is usually fine
 if the document displays well.
 <h2 id="newlines">Unix - DOS newlines</h2>
-Convert DOS (CR/LF) to Unix (LF) newlines within a Unix shell. See also <code>dos2unix</code> and <code>unix2dos</code> if you have them.
-<pre># sed 's/.$//' dosfile.txt > unixfile.txt
+Convert DOS (CR/LF) to Unix (LF) newlines and back <b>within a Unix shell</b>. See also <code>dos2unix</code> and <code>unix2dos</code> if you have them.
+<pre># sed 's/.$//' dosfile.txt > unixfile.txt                  <span class="cmt"># DOS to UNIX</span>
+# awk '{sub(/\r$/,"");print}' dosfile.txt > unixfile.txt   <span class="cmt"># DOS to UNIX</span>
+# awk '{sub(/$/,"\r");print}' unixfile.txt > dosfile.txt   <span class="cmt"># UNIX to DOS</span>
 </pre>
-Convert Unix to DOS newlines within a Windows environment. Use sed from mingw or cygwin.
+Convert Unix to DOS newlines <b>within a Windows environment</b>. Use sed or awk from mingw or cygwin.
 <pre># sed -n p unixfile.txt > dosfile.txt
+# awk 1 unixfile.txt > dosfile.txt   <span class="cmt"># UNIX to DOS (with a cygwin shell)</span>
 </pre>
 
 <h2>PDF to Jpeg and concatenate PDF files</h2>
@@ -2633,7 +2647,8 @@
 # lpr -Php4500 #2 unixtoolbox.ps     <span class="cmt"># Use printer hp4500 and print 2 copies</span>
 # lpr -o Duplex=DuplexNoTumble ...   <span class="cmt"># Print duplex along the long side</span>
 # lpr -o PageSize=A4,Duplex=DuplexNoTumble ...
-# lpq                                <span class="cmt"># Check the queue on default printer</span>
+</pre>
+<pre># lpq                                <span class="cmt"># Check the queue on default printer</span>
 # lpq -l -Php4500                    <span class="cmt"># Queue on printer hp4500 with verbose</span>
 # lprm -                             <span class="cmt"># Remove all users jobs on default printer</span>
 # lprm -Php4500 3186                 <span class="cmt"># Remove job 3186. Find job nbr with lpq</span>
@@ -2878,7 +2893,7 @@
 </div>
 
 <div id="scripting"><h1><a>Scripting</a></h1>
-<p class="xrefp"><a class="xrefp" href="#bournebasics">Basics</a> | <a class="xrefp" href="#bourneexample">Script example</a> | <a class="xrefp" href="#sed">sed</a> | <a class="xrefp" href="#regex">Regular Expressions</a> | <a class="xrefp" href="#shcmd">useful commands</a></p>
+<p class="xrefp"><a class="xrefp" href="#bournebasics">Basics</a> | <a class="xrefp" href="#bourneexample">Script example</a> | <a class="xrefp" href="#awk">awk</a> | <a class="xrefp" href="#sed">sed</a> | <a class="xrefp" href="#regex">Regular Expressions</a> | <a class="xrefp" href="#shcmd">useful commands</a></p>
 The Bourne shell (/bin/sh) is present on all Unix installations and scripts written in this language are (quite) portable; <code>man 1 sh</code> is a good reference.
 
 <h2 id="bournebasics">Basics</h2>
@@ -2964,6 +2979,15 @@
 <span class="keyword">exit</span> 0                                       <span class="cmt"># exit 0 means successful</span>
 </pre>
 
+<h2 id="awk">Some awk commands</h2>
+Awk is useful for field stripping, like cut in a more powerful way. Search this document for other examples. See for example <a href="http://www.gnulamp.com/awk.html">gnulamp.com</a> and  <a href="http://student.northpark.edu/pemente/awk/awk1line.txt">one-liners for awk</a> for some nice examples.
+<pre>awk '{ print $2, $1 }' file                  <span class="cmt"># Print and inverse first two columns</span>
+awk '{printf("%5d : %s\n", NR,$0)}' file     <span class="cmt"># Add line number left aligned</span>
+awk '{print FNR "\t" $0}' files              <span class="cmt"># Add line number right aligned</span>
+awk NF test.txt                              <span class="cmt"># remove blank lines (same as grep '.')</span>
+awk 'length > 80'                            <span class="cmt"># print line longer than 80 char)</span>
+</pre>
+
 <h2 id="sed">Some sed commands</h2>
 Here is <a href="http://student.northpark.edu/pemente/sed/sed1line.txt">the one liner gold mine</a><span class="fn">http://student.northpark.edu/pemente/sed/sed1line.txt</span>. And a good <a href="http://www.grymoire.com/Unix/Sed.html">introduction and tutorial to sed</a><span class="fn">http://www.grymoire.com/Unix/Sed.html</span>.
 <pre>sed 's/string1/string2/g'                    <span class="cmt"># Replace string1 with string2</span>
@@ -3051,7 +3075,7 @@
                                           <span class="cmt">// (*pobj).x and pobj->x are the same</span>
 </pre>
 <h2>C++ example</h2>
-As a slightly more realistic program in C++, let's create a class in its own header (IPv4.h) and implementation (IPv4.cpp) and create a program which uses the class functionality. The class has a member to convert an IP address in integer format to the known quad format. This is a minimal c++ program with a class and multi-source compile.
+As a slightly more realistic program in C++: a class in its own header (IPv4.h) and implementation (IPv4.cpp) and a program which uses the class functionality. The class converts an IP address in integer format to the known quad format.
 <h3>IPv4 class</h3>
 <h4>IPv4.h:</h4>
 <pre style="page-break-inside:avoid;"><span class="pp">#ifndef</span> IPV4_H
@@ -3061,8 +3085,7 @@
 <span class="keyword">namespace</span> GenericUtils {                          <span class="cmt">// create a namespace
 </span><span class="keyword">class</span> IPv4 {                                      <span class="cmt">// class definition
 </span><span class="keyword">public</span>:
-    IPv4();
-    ~IPv4();
+    IPv4(); ~IPv4();
     std::string IPint_to_IPquad(<span class="keyword">unsigned</span> <span class="keyword">long</span> ip);<span class="cmt">// member interface
 </span>};
 } <span class="cmt">//namespace GenericUtils</span>
@@ -3092,7 +3115,6 @@
 <span class="pp">#include</span> &lt;iostream&gt;
 <span class="pp">#include</span> &lt;string&gt;
 <span class="keyword">using</span> <span class="keyword">namespace</span> std;
-
 <span class="keyword">int</span> main (<span class="keyword">int</span> argc, <span class="keyword">char</span>* argv[]) {
     string ipstr;                                 <span class="cmt">// define variables
 </span>    <span class="keyword">unsigned</span> <span class="keyword">long</span> ipint = 1347861486;             <span class="cmt">// The IP in integer form</span>
@@ -3110,10 +3132,10 @@
 # ./simplecpp.exe 
 1347861486 = 80.86.187.238
 </pre>
-Use <code>ldd</code> to check which libraries are used by the executable and where they are located. This command is also used to check if a shared library is missing or if the executable is static.
+Use <code>ldd</code> to check which libraries are used by the executable and where they are located. Also used to check if a shared library is missing or if the executable is static.
 <pre># ldd /sbin/ifconfig</pre>
 <h2 id="makefile">Simple Makefile</h2>
-The corresponding minimal Makefile for the multi-source program is shown below. The lines with instructions <i>must begin with a tab</i>! The back slash "\" can be used to cut long lines.
+The minimal Makefile for the multi-source program is shown below. The lines with instructions <i>must begin with a tab</i>! The back slash "\" can be used to cut long lines.
 <pre style="page-break-inside:avoid;"><span class="pp">CC</span> = g++
 <span class="pp">CFLAGS</span> = -O
 <span class="pp">OBJS</span> = IPv4.o simplecpp.o
@@ -3153,7 +3175,7 @@
 <!-- <div class="pb" /> -->
 
 <div class="footerlast">
-This document: "Unix Toolbox revision 13.1" 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 13.2" 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.
 </div>
 
 </body>