Develop Reference

Why doesn't cd command work using Java JSch?

I'm just learning Java and Jsch, and I can get it to run other commands but not cd. The error code returned by the SSHManager sendCommand function is not null, but some unreadable string that is different every time (maybe that means it is null not that familiar with inner workings of Java).
Any idea why not? Similar question here JSch - Why doesn't CD work? but unanswered.
I won't copy and paste the whole SSHManager class here - useful answer with complete code here that I'm trying to follow. Run a command over SSH with JSch
Sample code below:
import SSH.SSHManager;
public class src
{
int ERROR = 0;
public static void main(String[] args)
{
String username = "debian";
String password = "temppwd";
String ipadd = "192.168.7.2";
SSHManager ssh = new SSHManager(username, password, ipadd, "");
ssh.connect();
String out = "";
//this doesn't work, printing output as bytes to show how weird it is
out = ssh.sendCommand("cd Desktop");
System.out.println(out.getBytes());
//some other test commands
out = ssh.sendCommand("mkdir test");
System.out.println(out);
out = ssh.sendCommand("ls");
System.out.println(out);
ssh.sendCommand("logout");
}
}
Output from the Eclipse Console (bin and Desktop are already there in root directory):
[B#b065c63
bin
Desktop
test

Each command executed over SSH "exec" channel (what is behind SSHManager.sendCommand) is executed in its own shell. So the commands have no effect on each other.
To execute multiple commands in the same shell, just use an appropriate syntax of your server shell. Most *nix shells use semicolon or double-ampersand (with a different semantics).
In your case, the double-ampersand would be more appropriate.
cd Desktop && mkdir test && ls
See also Multiple commands using JSch.
Though, if your want to read commands output, you will have problem distinguishing, where output of one commands ends and output of the following commands starts. Let alone if you wanted to check command exit code.
Then it's better to execute each command in its own "exec" channel in a way that does not require a context. In your case that means using full paths:
mkdir Desktop/test
ls Desktop
See also How to perform multiple operations with JSch.
Also as you were going to use file manipulation only, you actually should not execute shell commands at all. Use the standard SSH API for file manipulation, the SFTP.

The question has kind of an answer, in the comments. Every command in sendCommand uses it's own 'pipe', so it disconnects and starts over in each one.
A quick solution would be to send multiple commands in one one sendCommand, such as:
out = ssh.sendCommand("cd Desktop; mkdir test; ls; logout");
But the correct way is to use a session, such as https://stackoverflow.com/a/9269234/290036

I answered a similar question Using java jcabi SSH client (or other) to execute several commands in shell
My open-source API Maverick Synergy has a high-level API to execute multiple commands within a shell. Its currently designed for and works well with bash-type shells.

Error while running docker build command from java code

I am running docker build command from java using following code -
Process p = new ProcessBuilder("docker","build","-f",Dockerfile,"--build-arg",some arguments,"-t","com.test:t-v16",".").start();
But ut gives me error -
Docker build requires exactly 1 arguments.
When googled, it was mentioned, there should be a dot (.) In the end of command. I have added it and still facing the issue.
Same command works on command line.

That's because you need to give a space before the "." in your String array.
Can you try and check it now.
String[] createBaseImage = {"docker","build","-f",Dockerfile,"--build-arg",some arguments,"-t","com.test:t-v16"," ."}:

Run cmd-line in java fails

I am facing the following problem:
I am writing a java-application in Eclipse. Inside my application I want to start a cmd command:
C:/Users/User1/Content-Integration Testing Framework/JDBC Connector/bin/connect -h
The command 'connect -h' is a an enterprise internal application which works fine.
If I would use a comand line a would have to chance my current directory like that:
cd C:/Users/User1/Content-Integration Testing Framework/JDBC Connector/bin/
and afterwards I would just type connect -h
This works great. But I am not really shure how to execute this command within a java application.
Here they tell me how to run a cmd inside a java application:
How to use "cd" command using Java runtime?
But if I do that:
Runtime.getRuntime().exec("'C:/Users/User1/Content-Integration Testing Framework/JDBC Connector/bin/connect' -h");
Eclipse tells me:
java.io.IOException: Cannot run program "'C:/Users/User1/Content-Integration": CreateProcess error=2, Das System kann die angegebene Datei nicht finden
at java.lang.ProcessBuilder.start(Unknown Source)
It cuts my command at "Content-Integration".
can someone help me please?

You should use the version of exec() that takes multiple args via a String array.
Runtime.exec(String s) will split your string using a tokenizer (this is why quoting the string won't work, and why you see the behaviour you do). If you resolve the executable and arguments yourself, and pass each as an array element in the above e.g.
String[] args = new String[]{"executable", "arg1", "arg2"};
Runtime.getRuntime().exec(args); // don't forget to collect stdout/err etc.
then you will bypass Runtime.exec(String s)'s splitting behaviour.

Have you tried:
Runtime.getRuntime().exec("\"C:/Users/User1/Content-Integration Testing Framework/JDBC Connector/bin/connect\" -h");

This happens because your path contains spaces. Make sure to wrap it in "" and it will work.
Runtime.getRuntime().exec("\"C:/Users/User1/Content-Integration Testing Framework/JDBC Connector/bin/connect\" -h");

tdbloader on Cygwin: Gettging FileNotFoundException: d:\cygdrive\d\....\node2id.idn

I am completely new to Jena/TDB. All I want to do is to load data from some sample rdf, N3 etc file using tdb scripts or through java api.
I am tried to use tbdloader on Cygwin to load data (tdb-0.9.0, on Windows XP with IBM Java 1.6). Following are the command that I ran:
$ export TDBROOT=/cygdrive/d/Project/Store_DB/jena-tdb-0.9.0-incubating
$ export PATH=$TDBROOT/bin:$PATH
I also changed classpath for java in the tdbloader script as mentioned at tdbloader on Cygwin: java.lang.NoClassDefFoundError :
exec java $JVM_ARGS $SOCKS -cp "PATH_OF_JAR_FILES" "tdb.$TDB_CMD" $TDB_SPEC "$#"
So when I run $ tdbloader --help it shows the help correctly.
But when I run
$ tdbloader --loc /cygdrive/d/Project/Store_DB/data1
OR
$ tdbloader --loc /cygdrive/d/Project/Store_DB/data1 test.rdf
I am getting following exception:
com.hp.hpl.jena.tdb.base.file.FileException: Failed to open: d:\cygdrive\d\Project\Store_DB\data1\node2id.idn (mode=rw)
at com.hp.hpl.jena.tdb.base.file.ChannelManager.open$(ChannelManager.java:83)
at com.hp.hpl.jena.tdb.base.file.ChannelManager.openref$(ChannelManager.java:58)
at com.hp.hpl.jena.tdb.base.file.ChannelManager.acquire(ChannelManager.java:47)
at com.hp.hpl.jena.tdb.base.file.FileBase.<init>(FileBase.java:57)
at com.hp.hpl.jena.tdb.base.file.FileBase.<init>(FileBase.java:46)
at com.hp.hpl.jena.tdb.base.file.FileBase.create(FileBase.java:41)
at com.hp.hpl.jena.tdb.base.file.BlockAccessBase.<init>(BlockAccessBase.java:46)
at com.hp.hpl.jena.tdb.base.block.BlockMgrFactory.createStdFile(BlockMgrFactory.java:98)
at com.hp.hpl.jena.tdb.base.block.BlockMgrFactory.createFile(BlockMgrFactory.java:82)
at com.hp.hpl.jena.tdb.base.block.BlockMgrFactory.create(BlockMgrFactory.java:58)
at com.hp.hpl.jena.tdb.setup.Builder$BlockMgrBuilderStd.buildBlockMgr(Builder.java:196)
at com.hp.hpl.jena.tdb.setup.Builder$RangeIndexBuilderStd.createBPTree(Builder.java:165)
at com.hp.hpl.jena.tdb.setup.Builder$RangeIndexBuilderStd.buildRangeIndex(Builder.java:134)
at com.hp.hpl.jena.tdb.setup.Builder$IndexBuilderStd.buildIndex(Builder.java:112)
at com.hp.hpl.jena.tdb.setup.Builder$NodeTableBuilderStd.buildNodeTable(Builder.java:85)
at com.hp.hpl.jena.tdb.setup.DatasetBuilderStd$NodeTableBuilderRecorder.buildNodeTable(DatasetBuilderStd.java:389)
at com.hp.hpl.jena.tdb.setup.DatasetBuilderStd.makeNodeTable(DatasetBuilderStd.java:300)
at com.hp.hpl.jena.tdb.setup.DatasetBuilderStd._build(DatasetBuilderStd.java:167)
at com.hp.hpl.jena.tdb.setup.DatasetBuilderStd.build(DatasetBuilderStd.java:157)
at com.hp.hpl.jena.tdb.setup.DatasetBuilderStd.build(DatasetBuilderStd.java:70)
at com.hp.hpl.jena.tdb.StoreConnection.make(StoreConnection.java:132)
at com.hp.hpl.jena.tdb.transaction.DatasetGraphTransaction.<init>(DatasetGraphTransaction.java:46)
at com.hp.hpl.jena.tdb.sys.TDBMakerTxn._create(TDBMakerTxn.java:50)
at com.hp.hpl.jena.tdb.sys.TDBMakerTxn.createDatasetGraph(TDBMakerTxn.java:38)
at com.hp.hpl.jena.tdb.TDBFactory._createDatasetGraph(TDBFactory.java:166)
at com.hp.hpl.jena.tdb.TDBFactory.createDatasetGraph(TDBFactory.java:74)
at com.hp.hpl.jena.tdb.TDBFactory.createDataset(TDBFactory.java:53)
at tdb.cmdline.ModTDBDataset.createDataset(ModTDBDataset.java:95)
at arq.cmdline.ModDataset.getDataset(ModDataset.java:34)
at tdb.cmdline.CmdTDB.getDataset(CmdTDB.java:137)
at tdb.cmdline.CmdTDB.getDatasetGraph(CmdTDB.java:126)
at tdb.cmdline.CmdTDB.getDatasetGraphTDB(CmdTDB.java:131)
at tdb.tdbloader.loadQuads(tdbloader.java:163)
at tdb.tdbloader.exec(tdbloader.java:122)
at arq.cmdline.CmdMain.mainMethod(CmdMain.java:97)
at arq.cmdline.CmdMain.mainRun(CmdMain.java:59)
at arq.cmdline.CmdMain.mainRun(CmdMain.java:46)
at tdb.tdbloader.main(tdbloader.java:53)
Caused by: java.io.FileNotFoundException: d:\cygdrive\d\Project\Store_DB\data1\node2id.idn (The system cannot find the path specified.)
at java.io.RandomAccessFile.open(Native Method)
at java.io.RandomAccessFile.<init>(RandomAccessFile.java:222)
at java.io.RandomAccessFile.<init>(RandomAccessFile.java:107)
at com.hp.hpl.jena.tdb.base.file.ChannelManager.open$(ChannelManager.java:80)
... 37 more
I am not sure what node2id.idn file is and why is it expecting it?

The file node2id.idn is one of TDB's internal index files. It's not something that you have to create or manage for yourself. I've just tried tdbloader on cygwin myself, it it worked OK for me. I can think of two basic possibilities:
your disk is full
the TDB index is corrupted
If this is the first file you are loading into an otherwise emtpy TDB, the second possibility is unlikely. If you are loading into a non-empty TDB, try deleting the TDB image and starting again. Note that TDB by itself does not manage concurrent writes: if you have more than one process writing to a single TDB image, you must handle locking at the application level, or use TDB's transactions.
The final possibility, of course, is that your disk is flaky. You might want to try your code on another machine.
If none of these suggestions help, please send a complete minimal test case to the Jena users list.

How can I execute a Java program within a php script?

I am writing a simple web upload script.
The goal is to upload a file using php, and then calling a java program to process this file.
I have done the work for uploading the file, but I cannot get a java program to be successfully run from within the php script.
I have tried exec(), shell_exec(), and system() with no results.
For the command, I have used "java Test", "java < directory >/Test", "/usr/bin/java < directory >/Test", I have even set up the application as a jar file with no results. The actual line of code I have used is:
echo shell_exec("java Test");
Usually there is no output. However, if I have just shell_exec("java"), then the last line of the help from java ("show splash screen with specified image") is displayed, which shows that the command has been executed. If I use, for example, shell_exec("whoami") I get "nobody" returned, which is correct. The only thing the java file does is create a file so that I can see that the application has been successfully run (the application runs successfully if I run it on the command line). I have set the permissions for the java file to 777 to rule out any possibility of permission errors. I have been struggling with this for a while trying all sorts of options with no results - the file is never created (the file is created with an absolute path so it's not being created and I just can't find the file). Does anyone have any ideas?
Thanks.

I have been struggling with this for a
while trying all sorts of options with
no results - the file is never created
(the file is created with an absolute
path so it's not being created and I
just can't find the file). Does anyone
have any ideas?
What I think the problem is. Apache runs as "nobody" group??(apache user??) which will execute the java script which will try to create a file on disc somewhere. I assume it does not have permission to write to that location. you should chown that folder so that apache user can write to that folder.
==
First off I would like to point out to you that calling exec() from a script could really blow up your server. I would advice you to use something like redis(see below) instead.
==
Second I think I know what the problem is. You should first try to run the simple example below which worked fine for me.
==
First be sure permission are set right. Because apache runs as nobody(most of the times).
I tried this simple test myself on ubuntu with php installed from repo.
test.java
class test {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}
test.php
echo exec('java test');
Ran test.php
$ php test.php
Hello World!
==
Or you could try 1 of the following solutions(which would even be a better solution):
Write your java program as a webservice for example on top of atmosphere-spade-server(simple/embedded jar). This could be written insanely fast. But on high load this will not be best option I guess. Still I think this will be more than fast enough for you probably. Even this way it will be much faster as executing it, because you won't have the overhead running JVM. Could blow up your server, not as fast as exec()
Do a blocking pop/push from a redis(*nix) list structure. This will be pretty easy to write on *nux because there are client libraries for both java/php. The speed will best I guess because redis is written in C. I use redis myself.
Use a JMS like for example activemq. Also pretty easy to write because good library support. I have not used a JMS myself. I use redis solution. The speed I guess would be a little less then with redis solution.

I dont realy know, but i came a cross PHP-JAVA bridge maybe it can help
http://php-java-bridge.sourceforge.net/pjb/
Update:
I tested this with Jasper Reports, and it is working really nice. It will allow you to Extend Java classes with PHP or just use Java class lik it was PHP.
use java\lang\String as JString;
require_once("javabridge/java/Java.inc");
class String extends JString {
function toString () {
return "hello " . parent::toString();
}
}
$str = new String("Java");
echo $str->toString();
or
$temp = new Java('java.sql.Timestamp');
$javaObject = $temp->valueOf('2007-12-31 0:0:0');
$params = new Java("java.util.HashMap");
$params->put("text", "This is a test string");
$params->put("date",$javaObject);
More examples: http://php-java-bridge.sourceforge.net/pjb/FAQ.html

It's possible it has to do with the path that the exec is defaulting to. You may need to explicitly define your classpath with an absolute path to your .class or jar files when calling java.

<?php
$PATH="C:\Program Files\Java\jdk1.7.0_09\bin";
echo exec("javac theNameOfYourJavaProgram.java 2>&1");//shows # of errors
echo "<br />";
echo exec("java theNameOfYourJavaProgram 2>&1");//this line executes it
echo "<br />";
echo shell_exec("javac theNameOfYourJavaProgram.java 2>&1 ");//compiles it
?>