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cannot execute java class from bash script and also updatd the java_home to higher version and compiled the class in the lower version than mentioned

I had SunOs 5.10 unix server , where i had written a script to execute a java file which is as below
#!/bin/ksh -x
export JAVA_HOME=openjdk1.8.0_331/bin
$JAVA_HOME/java com.myclass.MyClient
in this script there is alot of code which includes log file, and other binaries class path added before exporting JAVA HOME. But when i am executing i am getting the below error
openjdk1.8.0_331/bin/java : Cannot execute
i had changes lot of java versions but getting the same error

Your JAVA_HOME is not an absolute path. This is broken; many tools will just fail when you do this. Just make it an absolute path. It may or may not explain your error, but it's a ticking timebomb.
JAVA_HOME cannot be bin; its the level above bin.
It looks like you're using JAVA_HOME as an ersatz script variable to make your script work, but this is wrong: JAVA_HOME is used by all sorts of tools and has a very specific meaning, and it's not whatever you think it is.
There are 2 obvious explanations for your error:
Some tool sees JAVA_HOME, attempts to run java based on this, and fails, because your JAVA_HOME is broken. There's a ton of infra that is 'custom' per OS, and it may well be that the SunOS setup didn't fail if you set JAVA_HOME to broken values, but it does fail here. The fix is to not have broken JAVA_HOME, not to start looking for a setup on your new OS that can deal with broken JAVA_HOME settings. In other words, your script was always broken, it just so happens that your specific set up on that specific server on that specific version of sun OS so happened to be capable of dealing with the mess.
A much simpler explanation is also possible: That executable does not run on your OS+Architecture combination. trivially testable: Do NOT set JAVA_HOME at all and just try to run that java executable by e.g. cd ing to the path and running ./java -version. See what happens. If that also gives you cannot execute, voila - the script isn't the problem (though it still has a broken JAVA_HOME you should be fixing), you need to install a JVM that works on your OS+Architecture.

Maven installation issues: JAVA_HOME should point to a JDK not JRE?

I'm super new to CS and very unfamiliar with UNIX/Bash vocab.
I'm currently trying to install Maven, and I made a few mistakes by copy pasting old installation instructions (with incorrect version numbers) and now the whole process is so messed up. I first tried to follow the given instructions on the website, that didn't work, then I tried a few other ones, and now I'm worried that I'm left with a mess by following different sets of instructions.
I've reached a point now where if I type in mvn -version I get the following:
The JAVA_HOME environment variable is not defined correctly
This environment variable is needed to run this program
NB: JAVA_HOME should point to a JDK not a JRE
Originally, my JAVA_HOME was set to jdk-install-dir, which still gave me the above error message. I tried redownloading the jdk (version 13.0.1) from Oracle, dragged that file to my home directory, and unzipped it. Then I set my JAVA_HOME to that unzipped file, jdk-13.0.1.jdk, and updated my PATH variable. After all this, I'm still getting this same error message, and I'm not sure what to do.
For the reference, here are what some relevant environment variables are set to (I didn't include irrelevant info from PATH):
~ echo $JAVA_HOME
jdk-13.0.1.jdk
~ echo $PATH
/usr/local/apache-maven/apache-maven-3.6.3/bin:/opt/apache-maven-3.6.3/bin:jdk-install-dir/bin:/usr/local/apache-maven/apache-maven-3.3.9/bin:/opt/apache-maven-3.6.3/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/allyson/apache-maven-3.6.3/bin:/Users/allyson/apache-maven-3.6.3/bin:jdk-12.0.1.jdk/bin:/Users/allyson/apache-maven-3.6.3/bin:JDK-13.0.1.jdk/bin
~ echo $M2
/usr/local/apache-maven/apache-maven-3.6.3/bin
~ echo $M2_HOME
/Users/allyson/apache-maven-3.6.3
One thing I'm curious about: for the M2 and M2_HOME variables, is it supposed to be that one is in my home directory (/Users/allyson) and one is for /usr/local?

OK, take a deep breath, and we'll walk through this. Each of these environment variables has a purpose, and once you understand what those purposes are, this makes a lot more sense. Mixing tutorials is not necessarily a problem, but you'll want to understand what you're doing, rather than just blindly copy values from the internet.
JAVA_HOME is intended to identify to the system environment where to find a java runtime environment. It needs to be set to the full path of where your JDK has been installed. On windows, this might be C:\Program Files\Java\jdk-13.0.1. On a Linux system, you have a bit more flexibility. Common locations might be /opt/java/jdk-13.0.1 or /usr/local/java/jdk-13.0.1. If you installed your JDK somewhere else, then you need to use that path instead. The message NB: JAVA_HOME should point to a JDK not a JRE refers to a common mistake when installing maven -- maven requires a JDK, not a plain JRE. This error is so common that any time JAVA_HOME points to a folder that isn't a JDK, it prints this warning (even if the folder in question isn't actually a JRE).
M2_HOME is supposed to be set to the full path where maven is installed (i.e. the place where you unzipped it). This more or less helps maven "find itself" if it should need to for whatever reason. Strictly speaking, this one isn't necessary. (It's not set on my system, and maven works fine for me). It's mostly a convenience for setting the next environment variable.
M2 is the full path to the folder where the maven executable is. This will almost always be $M2_HOME/bin, but it's certainly possible to do weird things, and this will let you work around those situations. Obviously, this won't work if you didn't specify $M2_HOME. This one isn't strictly necessary, either, and is mostly a convenient way of setting up the next one.
PATH is where your Linux system looks to find programs to run when you type their name on the command line. For ease of use, you'll want to make sure that the maven and java executables are included somewhere in the : delimited list. Most Linux distributions already have a default PATH set up for you in a shell resource file of some kind. You'll want to refer to their documentation for how to add another entry to the path, but a common idiom would be PATH=$PATH:$M2 (which would append the value of $M2 to the value of $PATH and then store the result back into PATH. If you didn't set up $M2 or $M2_HOME, you'll need to do something else.
So, TL;DR, if you installed your JDK in /opt/java/jdk-13.0.1 and unzipped maven into /opt/maven/apache-maven-3.6.3, your bear minimum working values are:
export JAVA_HOME=/opt/java/jdk-13.0.1
export PATH=$PATH:$JAVA_HOME/bin:/opt/maven/apache-maven-3.6.3/bin
And if you wanted a complete set
export JAVA_HOME=/opt/java/jdk-13.0.1
export M2_HOME=/opt/maven/apache-maven-3.6.3
export M2=$M2_HOME/bin
export PATH=$PATH:$JAVA_HOME/bin:$M2
It's worth noting that most Java IDEs will include a GUI for setting up maven and Java within the IDE (the settings will typically only work within that IDE). It's often much easier for beginners to get up and running that way.

$JAVA_HOME should be a full path, not the dir name.
scream#kafka1:~$ echo $JAVA_HOME
/opt/java/jdk-11.0.5/
scream#kafka1:~$

I'm working on Ubuntu 20, and my own issue was about the jdk version located in the JAVA_HOME variable, which wasn't the right version. This was my trip around that issue:
First, What is the JAVA_HOME value?
$ echo $JAVA_HOME
$ /usr/lib/jvm/jdk-11.0.10
Next question/step, where is the Java app pointing to?
(Source: https://stackoverflow.com/a/42706056/2373421)
$ java -XshowSettings:properties -version 2>&1 > /dev/null | grep 'java.home'
java.home = /usr/lib/jvm/jdk-11.0.12
So, the JAVA_HOME variable wasn't keeping the right value. Let's change that:
$ export JAVA_HOME=/usr/lib/jvm/jdk-11.0.12
The test outcome is right now:
$ mvn -v
Apache Maven 3.8.1 (05c21c65bdfed0f71a2f2ada8b84da59348c4c5d)
Maven home: /opt/apache-maven-3.8.1
Java version: 11.0.12, vendor: Oracle Corporation, runtime: /usr/lib/jvm/jdk-11.0.12

I'm doing this for future me's bc after all the links in StackOverflow, the solution was to check mvn.cmd file on C:\Program Files\Maven\apache-maven-3.6.3\bin...
On line 52 it sets the JDK, but it didn't had the "/bin" where my OpenJDK 15 stored the java.exe
This fixed the issue on Windows 11 but it could serve as an idea for other OS. Hope that it helps!

Installing and using Emscripten

I installed Emscripten through the steps shown below:
1.) Download the emsdk-portable version for Linux/MacOSX
http://kripken.github.io/emscripten-site/docs/getting_started/downloads.html#sdk-downloads
2.)
Run
$ ./emsdk update
$ ./emsdk install latest
$ ./emsdk activate latest
$ source emsdk_env.sh (To update your environment variables)
I believe everything installed correctly, however I am unable to run emscripten anywhere outside of the emsdk folder.
I need to be able to run em++ in my: Documents/project3/dataviz/graphiti folder.
Also, when I run em++ -v in my emsdk folder, I get the following message I have been unable to resolve:
Java does not seem to exist, requierd for closure compiler,
which is optional (define JAVA in /home/bryce/.emscripten if you want it)
I attempted to define the java path in the folder, but I'm not sure how it should look.
Any help resolving these two issues would be very much appreciated.

The first problem sounds like the PATH isn't being set correctly. Type echo $PATH after running source emdsk_env.sh and check that the path to your emscripten installation has been added.
Note that you have to export the PATH for each terminal session you're using (it might be an idea to put source <path to emsdk dir>/emsdk_env.sh in your .bashrc file so this gets done automatically).
Could this link help with the second problem?
https://kripken.github.io/emscripten-site/docs/building_from_source/verify_emscripten_environment.html#installing-missing-components

Does jna.library.path use any environment variables?

On OS X 10.8.2, I'm using JNA and gstreamer-java (through the Eclipse IDE) to load gstreamer libraries. At first I installed gstreamer using the SDK provided by gstreamer.com. However, I uninstalled this and use Macports to install it.
The SDK's libs were installed to:
/System/Library/Frameworks/GStreamer.framework/Versions/0.10-x64/lib
But that directory no longer exists.
Where Macports installed the libs to:
/opt/local/lib
Now, say I want to set java to know of this location via some environment variable. Is this possible? It seems so, because running this line:
System.out.println( System.getProperty("jna.library.path"));
Shows /System/Library/Frameworks/GStreamer.framework/Versions/0.10-x64/lib. But I cannot for the life of me figure out where that got set. It's not set as a runtime VM argument. My $PATH and $DYLD_LIBRARY_PATH, $LD_LIBRARY_PATH do not have this directory set. They actually have the path I want, /opt/local/lib/ set which has no effect it seems. Running env shows no variables with the Framework path either.
So, jna.library.path. Is it set externally? How can I change it--without setting it at runtime or via java command-line arguments? Zero points for telling me to symlink.
EDIT:
Searching through gstreamer-java's files led me to gstreamer-java.spec, which has this line:
sed -i [...] -e "s,\(run.jvmargs=-Djna.library.path=\).*,\1%{_libdir}:$(pkg-config --variable=pluginsdir gstreamer-0.10),"
Running the contained command pkg-config --variable=pluginsdir gstreamer-0.10 gets me this:
/opt/local/lib/gstreamer-0.10
Which is the correct path for plugins. Further running pkg-config --print-variables gstreamer-0.10 gives me all these:
typelibdir
datarootdir
exec_prefix
pluginsdir
datadir
prefix
libdir
includedir
girdir
toolsdir
Which are all at or under the correct /opt/local/ directory.

Have you tried running outside of Eclipse?

error when installing Java EE SDK on Linux

I did have JDK installed, and also put $JDK_HOME/bin on my PATH. However, I still have problem to install Java EE. Could you guys give me some hints? Thanks.
dav#Bruno:~$ ls
[some stuff...]
33511405_3645.jpg glassfish stuff
bea hplip-3.11.12-plugin.run temp
bin hpscan001.png Templates
C03_08.txt java_ee_sdk-6u4-jdk7-linux.sh Tomcat
c4c jdk1.7.0_10 Ubuntu One
[some stuff2...]
dav#Bruno:~$ echo $PATH
/home/dav/jdk1.7.0_10/lib:/usr/share/java:/home/dav/jdk1.7.0_10:/home/dav/jdk1.7.0_10/bin:/home/dav/Fluent.Inc/bin:/home/dav/bin:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/home/dav/jdk1.7.0_10/lib:/usr/share/java
dav#Bruno:~$ sudo sh java_ee_sdk-6u4-jdk7-linux.sh
Could not locate a suitable jar utility.
Please ensure that you have Java 6 or newer installed on your system
and accessible in your PATH or by setting JAVA_HOME
dav#Bruno:~$

I think the problem you're facing is that the PATH variable you're looking at is set for the user 'dav', but because you're sudoing the sh command, the PATH changes to that of root, which probably doesn't contain the JDK.
I think you should try explicitly setting the JAVA_HOME environment variable, try running:
sudo JAVA_HOME=/home/dav/jdk1.7.0_10 sh java_ee_sdk-6u4-jdk7-linux.sh

in case someone still gets frustrated over this:
("Could not locate a suitable jar utility.
Please ensure that you have Java 7 or newer installed on your system
and accessible in your PATH or by setting JAVA_HOME")
First of all make sure you are not using "sudo" to install java ee.
when you use sudo you use a different environment (root, with not necessarily the same
environment variables). in this case (ee installation) sudo is not required.
In other (which ever) cases when root access is required make sure the required user/system variables are set on system level, not (just) on user level.
to set variables at system level instead of user level define the variables in a system level script, i.e. /etc/profile or /etc/profile.d
otherwise, if you are not using SUDO trying to install jee, and still have this "JAVA_HOME not set"-problem, try this:
the cause seems to be the JAVA_HOME variable that can not be found by the install script.
therefore adjust ~/.bashrc to define JAVA_HOME.
JAVA_HOME of course has to point to your oracle java (se/jdk) installation. If you haven't installed it, that's the first thing to do. JAVA_HOME should point at the root directory of the installation (not to the bin directory in it), i.e.:
export JAVA_HOME=/usr/local/jdk1.7.1_02.
Next change path like so:
PATH=$JAVA_HOME:$JAVA_HOME/bin:$JAVA_HOME/jre/bin:$PATH
keep the faith
don't let frustrations get the better of you (perhaps making you take it out on your colleagues or loved ones :o )
don't allow stress to build up too much. take a break in time to watch a funny video or
take a stroll to the coffee machine, or have a little chat with that cute person a couple of desks away from you.

You'll need to create an update alternative for the "jar" executable like:
sudo update-alternatives --install "/usr/bin/jar" "jar" "/usr/lib/jvm/jdk1.6.0/bin/jar" 1
Note: You may need to use appropriate path in your case.