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How Do I Install a Jar?

I was reading some documentation for db2jcc4.jar when something caught my attention in the following (emphasis added):
The following command will retrieve the JCC driver version if executed from the command line:
java com.ibm.db2.jcc.DB2Jcc -version
Or for drivers that are not yet installed:
java -cp ./db2jcc.jar com.ibm.db2.jcc.DB2Jcc -version
All I have is the db2jcc4.jar file - it didn't come with an installer or anything. I can run the second command and it works fine, but the first gives me this stack trace:
Exception in thread "main" java.lang.NoClassDefFoundError: com.ibm.db2.jcc.DB2Jcc
Caused by: java.lang.ClassNotFoundException: com.ibm.db2.jcc.DB2Jcc
at java.net.URLClassLoader.findClass(URLClassLoader.java:434)
at java.lang.ClassLoader.loadClassHelper(ClassLoader.java:665)
at java.lang.ClassLoader.loadClass(ClassLoader.java:644)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:358)
at java.lang.ClassLoader.loadClass(ClassLoader.java:627)
Could not find the main class: com.ibm.db2.jcc.DB2Jcc. Program will exit.
This tells me that the jar is not yet installed. In all the time I've worked with Java, I've never heard of installing a jar. How can I make it so that the first command works instead of having this issue and printing a stack trace? How can I install a jar?
It looks to me like the second command includes a flag, -cp, which modifies the classpath. I'm guessing that means that all I need to do is move my jar file into a specific directory. I tried putting it in /usr/lib/jvm/java-1.6.0-openjdk-1.6.0.33.x86_64/jre/lib but that didn't make it so the second command would work. I'm stumped and would appreciate any suggestions for where exactly I need to move this jar for it to be considered installed.

There is no such thing as "installing" a jar. To be used by a Java application, jars have to be accessible in the classpath. Take a look at this link:
http://docs.oracle.com/javase/tutorial/essential/environment/paths.html

By installing the java jar they meant that the jar is available to your program (physically present and found in your class path). If the Path to the jar was not setup then you have to options:
+ copy the jar file to your existing path
+ include the jar file in the command line
java -cp <path_to>/db2jcc.jar com.ibm.db2.jcc.DB2Jcc -version

It looks to me like the second command includes a flag, -cp, which modifies the classpath. I'm guessing that means that all I need to do is move my jar file into a specific directory.
I would say that you need to explicitly include the jar file itself on the classpath. Personally, I generally do not attempt to "install" a jar as you describe, but rather create some sort of script or executable jar file that will facilitate the establishment of the correct classpath.
EDIT: In the context of deploying code to an application server, then "installing" the jar would make sense--typically there's a shared lib folder available on an application server where you can simply drop the jar and the code will become available to all the applications running on the server--this can become a bit of a management headache, however and I often will prefer to have a completely self-contained deployment over sharing jar files between applications--YMMV, however.

You commented thus:
Your link has this comment - (Classes that are part of the JRE, JDK platform, and extensions should be defined through other means, such as the bootstrap class path or the extensions directory.) - How would I go about adding the jar through that?
That is a bad idea, for (at least) the following reasons:
Putting stuff into the extensions directory is going to potentially affect every Java application that you execute. Not just the application that you are trying to "install". In some cases, this may to lead to unexpected breakages due to conflicting versions, etcetera.
When you update the Java installation, the standard installer, RPM or whatever is going to create a new installation tree. But it won't copy anything from the existing installation. So a Java update is likely to break any application that depends on stuff in "extensions".
If you try to solve the above problems by "embedding" a Java installation, you risk losing track of where your Java installations are. This makes applying Java security patches problematic. And of course, embedded JREs take up a lot of disc space ... at ~100Mb a time.

I suspect that "Installing a JAR" is a poorly chosen terminology that likely means placing the jar on the JVM classpath" - i.e. in order to make it available to an application. The recommended ways of doing so vary depending on the Java platform (whether it is a server platform or a client side platform).
For example, on a Java EE server, you could package the jar file within the application, or define it as a shared library, and attach it to the server's classloader or the application's classloader to make it available to that application. Third party applications, such as various IBM products, will come with their own instructions as to how to 'install' a db2jcc4 driver.

What needs to be set up on Unix for a java web client?

I created a client using proxy in Oracle JDeveloper to call web service. JDeveloper deployed automatically and the code works well under windows environment. But now I'm required to migrate the code to unix server. I deployed the project to a .war file and copy it to unix which cannot be executed correctly using "jar" command.
Could anybody give me a whole picture or a high-level step-by-step instruction about what I need to set up to execute war on unix? I'm new to this area, and for now I got some suggestions like installing a Tomcat first.
What I have now:
1. a war file including .class, .java, WEB-INF, META-INF, MANIFEST.MF deployed from JDeveloper
2. JDK 1.6.0_25 installed on unix usr/java/
3. Tomcat installed on unix, but not under bin or local or usr directory(is it ok?)
Some specific questions:
1. what else do I need?
2. where to drop the .war?
3. do I need to unzip or re-compile the war?
4. how can I run the main class in the war?
Errors poped-up now:
1. cannot find main class
2. I tried to un-zip war and compile the class including main, and get "cannot find symbol" for the webservice specified classes' name.
Thanks to whoever attempt to help!

Even though this question probably should've been asked on ServerFault instead of here, sounds like you got all you need. Try dropping the .war on tomcat's webapps directory.

You should be able to just drop the .war file in $CATALINA_BASE/webapps and tomcat should pick it up when you start it.
$CATALINA_BASE is where you installed tomcat, unless you've configured tomcat for multiple bases.

You only need a war file if you are developing web application. From what you describe, you need to create a zip file which contains all the libraries and classes you need and copy it to Unix. Then you unpack it and execute it using java command.
Alternatively you can create a jar file with all dependencies included using Maven Shade Plugin and execute your code using jar command.

Can not put anything into /var/lib/tomcat7/webapps/

I was starting on JAVA web development today and encountered some problems, I installed my tomcat7 on my ubuntu machine. Now when I browse to //localhost:8080, I get the default welcome page saying:
This is the default Tomcat home page. It can be found on the local filesystem at: /var/lib/tomcat7/webapps/ROOT/index.html
Tomcat7 veterans might be pleased to learn that this system instance of Tomcat is installed with CATALINA_HOME in /usr/share/tomcat7 and CATALINA_BASE in /var/lib/tomcat7, following the rules from /usr/share/doc/tomcat7-common/RUNNING.txt.gz.
But strangely when I try echo $CATALINA_HOME nothing shows up.
Also I can not copy/create anything in the default /var/lib/tomcat7/ROOT though it's just a matter of providing few permissions but I was wondering whether it is the right way to do it?,
What I would like to do is create a separate directory in my home where I can put my web application and tomcat can read hem from there. Is there a way to do it? In apache I can do it by changing the document-root and directory but I don't know how to do it for tomcat

But strangely when I try echo $CATALINA_HOME nothing shows up.
This is because the packaged version sets CATALINA_HOME just prior to launching Tomcat, after reading it from a configuration file (typically somewhere in /etc).
Also I can not copy/create anything in the default
/var/lib/tomcat7/ROOT though it's just a matter of providing few
permissions but I was wondering whether it is the right way to do it?
The permissions problem has to do with you not being root (or the Tomcat user). Most packaged Tomcat installations (deb or RPM) tend to install with a specific user in mind, and copying stuff in as a different sometimes won't work.
/usr/share/tomcat7 is your CATALINA_HOME directory, and it has links to the other directories, such as /var/lib/tomcat7/webapps, /etc/tomcat7, etc. You shouldn't copy directly into a web application, you should package the web application into a WAR file and "deploy" it. The advantages are numerous.
What I would like to do is create a separate directory in my home
where I can put my web application and tomcat can read hem from there.
Is there a way to do it?
Yes, one is created when "deploying a web app". Look to the standard Tomcat7 documentation, and consider installing the "manager" web application if you like a non-command line interface. Now that you know what "installation" of a web app is called, it will likely be an easier task.
In apache I can do it by changing the document-root and directory but
I don't know how to do it for tomcat
Tomcat has a different, slightly more restrictive set of requirements for a document-root. You need to learn it, and just come to terms with the idea that it's never going to be the same. Basically under the "webapps" directory, is a WAR file or a expanded directory that came from a WAR file. Editing in-place is not a good idea for Tomcat, as the CGI-equivalents are not read from disk each time they are ran, they are linked into the memory of Tomcat. This means that a change in the directory might not affect your web application, which is good enough reason to not bother changing the on-disk files for a deployed web application.
Modify the web application, repackage it, and update the deployment. It's really the "right" way to go with Tomcat.

Give permission 777 to the webroot folder
sudo chmod -R 777 Webroot
After moving to the tomcat folder

Configure Servlet, JSP with Tomcat 7

I am beginner in Java EE and when I install Tomcat 7, its works fine, I can access http://localhost:8080.
Now I understood that servlet and jsp jars files come under tomcat 7 and no need to download from oracle site.
So my question is when I compile my first servlet, it's say import javax.servlet.*; and import javax.servlet.http.*; not found.
How can I solved this?
Also one more thing In that servlet, I am also looking for visited user ip address. So I can know the location of that user.
I am using window platform and I configured JDK properly and its work fine.

hmmm, this is common question for beginner in Java EE, even I was too. Don't worry, here I am explaining you - How to solve this problem?. Here I am assume that you know How to install and configure tomcat 7, if not, visit http://www.coreservlets.com/Apache-Tomcat-Tutorial/
Basically tomcat 7 (even old one) come with servlets and jsp jars, you can find those jar in tomcat's lib folder
Tomcat 7.0\lib
servlet-api.jar
jsp-api.jar
Now you need to place these files in classpath (let me know if you don't know How to set files in classpath) By default tomcat not setting classpath for servlets.
After that if you compile your java file, it should works. let me know if you face any problem or difficulties.
if you want user location, you need to use request.getRemoteAddr() and it will give you the ip address, regarding location name (city, state, country and even more information), please visit http://www.maxmind.com/ services.
Here is the some links
http://www.maxmind.com/app/geolitecity
Example - http://geoip.cvs.sourceforge.net/viewvc/geoip/java/CityLookupTestV6.java?view=markup

If you are compiling using command line window, you have to specify class path for the servlet-api.jar in the lib directory of the tomcat installation directory or servlet-api.jar should be added to the windows class path. For using in command line,
javac -classpath <tomcat-installation-directory>/lib/servlet-api.jar myapp.java
If you are using IDE, need to add the server to the IDE and/or set the runtime environment to Tomcat.

CLASSPATH, Java Buld Path (eclipse), and WEB-INF\LIB : what to use, when, and why?

I recently switched to J2EE from .NET, and am confused about where to put JAR files. I know that the CLASSPATH, WEB-INF, and Eclipse's Java Web Path are all places where JARs can be stored, but I'm confused about which folder to use, when, and why.
First off, we have the CLASSPATH. I usually set this by going into "Environment Variables" inside "My Computer." I know that this is the default place where the Java compiler looks for JAR files. When I add a folder or a JAR to my CLASSPATH environment variable, why is it ignored by Eclipse, the Java compiler, and the web server?
Also, I know that WEB-INF\LIB is a place where you can put JAR files that your web app is going to use. However, I've put JARs in WEB-INF\LIB only to have them be ignored. In what situations should I put JARs into WEB-INF\LIB folder? How do I get Eclipse or the web server to notice them?
So far, the only thing that works for me is to actually change the Java Build Path for an Eclipse project. I'll select the JARs I need and hit "Add External JARs." Most of the time when I do this, Eclipse will recognize my JARs and read the classes therein. However, I've run into a bunch of weird random errors while doing this (mostly having to do with dependencies, I think). For some reason, I just get the feeling that this isn't the right way to do things, and that I'm missing some vital piece of information. When should I be manually Adding External JARs inside Eclipse, and when should I be doing things differently? How come Eclipse's Java Build Path doesn't seem to know about the folders in my CLASSPATH environment variable?
Really, I would just like to gain a better understanding of the CLASSPATH, Eclipse's Java Build Path, and the WEB-INF/LIB folder -- the purposes they serve, the relationships between them, and where I should be putting my JARs in various situations. I would appreciate any advice you could give me, or any articles that you could recommend.
Thank you.

The CLASSPATH you set in your environment affects only standalone Java applications, i.e. ones you run from a command prompt or an icon. As you've noticed, Eclipse ignores this. It sets up its own per-project classpaths.
javac and java, if called from the command prompt, should/may honor this path, but it's no longer considered great practice to do this. It's turned out that every app needs its own set of stuff, so a global CLASSPATH isn't really doing any of them any good. Modern practice is to simply specify the classpath with the -cp option on the command line for javac or java.
A standalone Web Application server will also set up its own classpath. From the command line or GUI, WebAppServers are usually started by a script (.BAT or .sh) that sets up a classpath using -cp. Tomcat has a directory called common or common/lib where it expects to see libraries that should be available the the server and all programs running under it. But you will generally not need/want to mess with this, as it's customaries for applications to provide their own library collectons in WEB-INF/lib.
So for a Web app, you'd put your varous jars into the lib directory, under WEB-INF, assuming Eclipse pre-builds such a directory structure for you.
All the libs you need also need to be made known to Eclipse. In the Project Explorer, I select the whole slew of them at once, right-click and select Build Path | add to build path. That's easier than messing with Eclipse's project build path manually.

Java has a long history and experience has shown that some ideas were good and some were bad.
The CLASSPATH environment variable was the initial way to tell the Java machine where to locate classes from your program, and works reasonably well for command line programs. It was rapidly found that this should not be a global thing (as that tend to mess things up in the long run) but a per-program thing. This could be done by creating a wrapper script/BAT-file which sets the variable and runs the Java machine.
All was well, then people wanted to write web server stuff in Java. The Servlet API was created where a web application is a stand-alone unit - this resulted in that the CLASSPATH for each web application is the unpacked files under WEB-INF/classes plus the jar-files under WEB-INF/lib. And only that. This means the global CLASSPATH variable is ignored. This has been found to be a VERY good thing, so the concept has migrated elsewhere.
For instance a "executable jar" (which Eclipse calls a "runnable jar") which is invoked with "java -jar foobar.jar" contains the complete classpath INSIDE the Jar in a special manifest file. Java Web Start which is used to start java programs from a web server explicily lists the full classpath in the configuration file on the server.
But, to get you started. If you want to write a Java web application:
Get the Eclipse Java EE version.
Create a new Dynamic Web Project e.g. named foobar.
Drag and drop (or copy/paste) the jar files you need in foobar/WebContent/WEB-INF/lib
Create a new file named foobar/WebContent/index.jsp. In the blank file type <h1>Hello World <%= new java.util.Date() %></h1>
Right click in editor for index.jsp, choose Run -> Run on Server, and choose the Basic -> J2EE preview at localhost server, and Finish.
A browser window will now open, either in a browser or inside Eclipse which will render your JSP-page. You can change the JSP-page, save it with Ctrl-S and reload the browser window to see the changes.

Also, I know that WEB-INF\LIB is a place where you can put JAR files that your web app is going to use. However, I've put JARs in WEB-INF\LIB only to have them be ignored. In what situations should I put JARs into WEB-INF\LIB folder? How do I get Eclipse or the web server to notice them?
The real problem you have here is likely that you didn't got Eclipse for Java EE developers and/or that you just created a generic Java Project instead of a Dynamic Web Project and built up the necessary folder structure yourself.
If you create a Dynamic Web Project in Eclipse for Java EE developers, then Eclipse will automagically add any libraries in WEB-INF/lib to the build path. The build path is roughly said just the classpath which is been used in both compiletime and runtime. With other words: just drop the 3rd party JAR's in there, really nothing more needs to be done.
Note that Java is case sensitive, thus it should be really called WEB-INF/lib, not WEB-INF/LIB. But anyway, if you create a Dynamic Web Project, then Eclipse will just automagically generate the correct folder/file structure for you.
As said by others, ignore the %CLASSPATH% environment variable. It is only used by javac.exe/java.exe and even then only when you do not specify any of the -cp, -classpath or -jar arguments. In real world this environment variable is seldom used, it is just some convenience for starters (and unfortunately also the most confusing one, they should never have invented it).

If you're dealing with web applications, /WEB-INF/lib is the portable place to put JARs. This is where web servers servlet containers expect to find an application's jar files.

Eclipse requires you to specify the path to your libraries, jar files (on Properties -> Java Build Path -> Libraries tab). This can be found on the .classpath project file.
Usually you have the JRE libs on its path (which would be on your classpath too), so adding the libs to the classpath and updating eclipse build path would work.
The WEB-INF directory should be the place that contains necessary information for your web application.

I'm not an Eclipse expert, but I think that your problem can be answered like this:
1) CLASSPATH is an environment variable that is read in when you launch java programs and is used by classloader to figure out where the classes are placed.
I would modify the CLASSPATH variable only in the case when you are launching an java program from a script, as this allows you to conveniently launch a program and make sure that the classes are found. This would not be the case for you, as you are developing the web application.
2) WEB-INF/lib is the directory under which the web application container's classloader (like tomcat or glassfish) looks into if your web application needs to resolve a class. So you put there the classes that are used in your web application.
Some IDE's do include the libraries/.jar files that you are using in a project automatically to the package.
3) Eclipse library/classpath resolving during the development time. I would assume, but apologies for assuming, as one really shouldn't do this ;), that you can define a library (add external .jar files to projects) and autocomplete/all the other interesting features should start working with this, as you basically make those classes visible for the IDE with that activity. I also would assume that you can then mark those libraries to be automatically added to the web projects etc., by the IDE.
In general a good reading about how classes are found during execution is here (it's a sun's official documentation). Also a good place to read about this is the ClassLoader class documentation.

Taken together the comments helped me as well. I had added all the jena .jars to the build path from eclipse but that wasn't sufficient. Following suggestion to "add to WEB-INF/lib" it seemed intuitive to drag from libraries folder to WEB-INF (from within eclipse), but that didn't work. Nor did copying the .jars to WEB-INF. I eventually drag-and-dropped from the windows desktop to the WEB-INF lib folder in Eclipse, and that fixed the problem. It would be nice if any .jars added to the build path were automatically copied to WEB-INF lib by Eclipse. In case it matters, this was eclipse EE IDE, Indigo release, on windows 7.