Changes

There are a few "classic problems" that students can encounter with their virtual machines and their host machine after performing lab2. Although all OPS235 OPS245 students may not encounter these problems, it is good to be aware of what a potential problem may look like, and know how to solve that problem.

#Boot-up your '''centos1''' VM. '''when When the Grub Boot menu appears''', press the letter <b><code><span style="color:#3366CC;font-size:1.2em;">e</span></code></b> (for "edit").

#Issue the command: <b><code><span style="color:#3366CC;font-size:1.2em;">passwd root</span></code></b> in order to change your root password (press '''ctrl-c''' if you wish to abort - i.e. not change password).<br>'''NOTE:''' if you are using SELinux in '''enforcing''' or '''permissive''' mode, you will also need to issue the command: '''touch /.autorelabel'''. <br>This may take some time depending on the amount of files you have on the file system (usually about 2 minutes).

# Go to an appropriate webpage and download a "zipped tarball" (compressed source code) for the '''lbreakout2''' game (filename should be something like: '''lbreakout2-2.6.5.tar.gz''')

# Use the '''tar''' command to decompress the "zipped tarball" called something like (not may be exactly): '''lbreakout2-2.6.5.tar.gz'''.

<li>Issue the command in step 78. You should get another ERROR! What dependency is missing?</li><li>Issue the following command to install the library files for SQL by issuing the command:<br><b><code><span style="color:#3366CC;font-size:1.2em;">sudo yum install SDL-devel</span></code></b> (possibly <b><code><span style="color:#3366CC;font-size:1.2em;">sudo yum install libpng-devel</span></code></b> and <b><code><span style="color:#3366CC;font-size:1.2em;">sudo yum install zlib-devel</span></code></b> )</li>

<li>You need to run a command to make this program available regardless of your current directory (as opposed to running command in the directory that contains the program). Login as root (be sure to be in the same directory as the source code after logging in as root) and So, issue the command:<br><b><code><span style="color:#3366CC;font-size:1.2em;">sudo make install</span></code></b></li>

{{Admon/tip|Bash Shell Scripting Tips:|<br>'''<u>The Here Document</u>'''<br><ul><li>A neat little trick involving a special type of redirection of stdin symbol: '''&lt;&lt;''' that allows input to be redirected to a command from within the command.<br><br> </li><li>Examples:<br><br>''cat &lt;&lt;+<br>This is a test message<br>This is the second line<br>+''<br><br>''mail -s "test message" youremailaddr &lt;&lt;+<br>This is a test message<br>I hope you like it.''<br>+<br><br>''tr [a-z] [A-Z] &lt;&lt;+<br>i like ops235<br>i love scripting.<br>+''<br><br></li></ul>'''<u>Using sed to Manipulate Text</u>'''<ul><li>The Linux command '''sed''' stands for <u>'''S'''</u>treaming <u>'''Ed'''</u>itor which is an effective way to manipulate a text file, output sent from a command, or from within a "here document". This command can manipulate matching text on a variety of criteria (such as '''line number(s)''', '''regular expression match''', etc). Commands can then be used for manipulation such as '''omitting''', '''printing''', '''substituting''', '''adding''', and '''inserting''' text.<br><br></li><li>The sed option '''-n''' suppresses display of text so the print ('''p''') command can be used; otherwise, the text will be displayed (with edits via the sed command instructions).<br><br></li><li>Results of text manipulation with sed can be stored in a variable using command substitution, or redirected to a file. '''NEVER redirect the stdout from a sed command to the same input file (or the input file will be destroyed)!''' <br><br></li><li>Examples<br><br>''sed 's/&#124;/ /g' &lt;&lt;+<br>I&#124;like&#124;weekends!<br>+''<br><br>''sed 's/$/\n/g' &lt;&lt;+<br>This text<br>should be<br>double-spaced!''<br>+<br><br></li></ul>}}

===Part 3: Generating Sofware Package Information with Shell ScriptsUsing sed to Filter Output from Commands===We will continue with using shell scripts commands to create a Software Information Report that manipulates output generated by the '''rpm''' command. The '''sed''' and '''awk''' commands are very useful tools in shell scripting to manipulate text. In this lab, we will be using ''sed'' to allow the user to select certain portions from the rpm command (options -qi).

rpm -qi $1 | sed -r -n "xchat</^($processedChoice)b></ p" &gt;&gt; span></rootcode><br /package>Notice that using the '''-i''' option with '''-infoq''' causes rpm to generate more output than we have seen from it so far.txt<br/li><brli>cat &lt;&lt;+Pick any five packages and run the <brcode>File <span style="/root/packagecolor:#3366CC;font-infosize:1.txt1em;" has been created><brb>rpm -qi</b>+<br/span></code>command on all five at once. This should produce dozens of lines of output. Consider the output it would generate if we used -a instead of picking just a few packages. <olli>Run <code><li valuespan style="8color:#3366CC;font-size:1.1em;">Save, set permissions, and then run that shell script for the application '''gedit'''. Did it create that report? Try running the script without an argument - What did it do? <lib>Use the rpm -qia</b><code/span>wget</code>now.</bli><li> command That is way too much output for us to downloadreasonably search through, study, and run but we have commands that can filter this down to a much more readable amount.</li><li>Try the following shell scripts on-linecommand:<blockquote><bbr><code><span style=" pointer-events:none;cursor:default;color:#3366CC;font-size:1.2em1em;">https<b>rpm -qia | sed -nre '/^Name&#91;&#91;:space:&#93;&#93;+:/p' -e '/ict.senecacollege.ca^Install Date&#91;&#91;:space:&#93;&#93;*:/~ops235p'</labs/packageInfoGraphical.bashb></span></code><br /b></blockquote>Instead of printing every line, this will only display the name and install date of each package.</li><li>Try modifying that command to understand what this Bash Shell script doesdisplay only the package Name and License.</li></ol>

Now that we have added some powerful logical structures to our python scripts, we can make our scripts much more adaptable. Just like we have done in bash, our Our python scripts can now responde respond to different situations by executing different code, or repeating the same code several times (e.g. keep asking the user for input until they give us something useful). In this investigation you will write a python script that will prompt a user for a directory to archive, ask them if they want the archive compressed, and (only if they do want compression) what type of compression to apply.

<li>Add a fourth prompt asking the user what type of compression they want (present them with gzip, bzip2, and xz xzip as options). Note that this prompt should only be shown if the user opted for compression (if they don't want compression, there is no point asking what type they don't want).</li>

<li>Add loops around your prompts for whether or not the user wants compression, and the compression type to make the script repeat each prompt until the user gives a response your script can actually use. Don't worry about doing anything with the archive name or path.</li>

# Switch to your <u>'''c7host'''</u> machine, open a shell terminalas a regular user, and use change to the directory: '''~/bin'''# Download the Lab 3 check script: <b><code><span style="color:#3366CC;font-size:1.2em;">sudo wget https://raw.githubusercontent.com/OPS245/labs/main/lab3-icheck.bash</span></code></b> to switch to a root session.# Change to the directory: <!--<br>For Andrew'''/root/bin'''# Issue the Linux commands sections use this script instead: <b><code><span style="color:#3366CC;font-size:1.2em;">wget httpshttp://ict.senecacollegelittlesvr.ca/~peter.callaghan/ops245/labs/lab3-check-andrew.bash</span></code></b>-->

# Run the shell script with <code>sudo</code>, and if any warningsappear, make fixes fix the issues noted by the script and re-run shell script rerun the check until you receive the "congratulationsCongratulations!" message.#Arrange proof of the following on the screen:<br><span style="color:green;font-size:1.5em;">&#x2713;</span> '''centos3''' VM:<blockquote><ul><li> Archived files '''created'''</li><li>Archive files '''restored'''</ul></blockquote><span style="color:green;font-size:1.5em;">&#x2713;</span> '''c7host''' Machine:<blockquote><ul><li> '''One repository added''' for yum</li><li>Run the '''lab3-check.bash''' script (must have all <b><code><span style="color:#66cc00;border:thin solid black;font-size:1.2em;">&nbsp;OK&nbsp;</span></code></b> messages)</li></ul></blockquote><span style="color:green;font-size:1.5em;">&#x2713;</span> '''Lab3Lab 3''' log-book logbook pages filled out.#Upload a screen of the proof from the previous step, along with the file generated by '''lab3-check.bash''', your log book, and your '''tarchiver.py ''' script to blackboard.