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.
Related
I made a little program and it worked fine, but now. First, it mux the xml chapter file in the mkv file, so we get a muxed mkv file. Some day ago I updated java to 1.7.21 and I think this is the problem why it is not working now. It's a little strange, but when I run in netbeans everything is fine, but when I build and I run the .jar file, it is not working. It create the xml file, but not mux in the mkv file (and because not muxed not delete the xml file). Here is the code: (filename=xml file path; mkv=mkv file path)
public void muxing() {
try {
Runtime rt = Runtime.getRuntime();
Process p = rt.exec("c:\\Program Files\\MKVtoolnix\\mkvpropedit.exe --chapters \""+filename+"\" \""+mkv+"\"");
if (p.waitFor()==0) {
File xmlfile=new File(filename);
xmlfile.delete();
}
}
catch(Exception e) {
System.out.println(e.getMessage());
}
}
The program worked with java 1.6 and I think with 1.7.17 too. Win7 32bit. Sorry for my bad English.
Oracle has made breaking changes to Runtime.exec() in Java 7 update 21 (and 6 update 45).
If the program name contains spaces, you need to specify command and arguments in an array:
Process p = Runtime.getRuntime().exec(new String[] {
"C:\\Program Files\\MKVtoolnix\\mkvpropedit.exe",
"--chapters", "\""+filename+"\"", "\""+mkv+"\""});
Another option is to use java.lang.ProcessBuilder:
Process p = new ProcessBuilder("C:\\Program Files\\MKVtoolnix\\mkvpropedit.exe",
"--chapters", "\""+filename+"\"", "\""+mkv+"\"").start();
As stated by Oracle:
Applications that need to launch programs with spaces in the program name should consider using the variants of Runtime.exec that allow the command and arguments to be specified in an array.
Alternatively, the preferred way to create operating systems processes since JDK 5.0 is using java.lang.ProcessBuilder. The ProcessBuilder class has a much more complete API for setting the environment, working directory and redirecting streams for the process.
I have build a Java command line application which consists of several moduls. So when you start the application via the command line, you have to pass one parameter and its options like this for example:
cmd-> java -jar application -startModul1 option1 folderPath
OR
cmd-> java -jar application -startModul5 500 folderPath 1222
Currently I have to start each modul by starting the application and passing the requested parameter+options. For now thats finde but later, when I have lets say 20 modules, I want to generate a proccess chain with several moduls started one after the other.
For example at the end I could start both modules from the example above with just one command.
cmd-> java -jar application -startAllModules option1 500 folderPath 1222
Is there a framework, where I can generate such a proccess chain with existing command line modules? This should not be NOTHING programatically because I want to have some sort of xml-file or whatever, where I just configure a process chain and where I can select the modules and its parameters that should be run with one command.
Have you thought of turning your program into an interpreter?
I think that parsing your command line, understanding what simple commands it must execute (from the xml you want to use) and launching them is enough.
How to launch them?
Process p = Runtime.exec(String[] cmdarray)
where cmdarray will have each of the words of the command:
{"java", "-jar", "application", "-startModul1", "option1", "folderPath"}
and
p.waitFor();
if you want this thread to wait until launched command ends.
Update: non concurrent
The later was in case you want to run several independent processes in parallel. One for command you need.
In case you only need to execute them one after the another there's a more simply way. When the main realizes it must execute multi modules, it calls itself with the appropiate arguments.
public static void main(String[] args) throws Exception {
// parse params
if (it's a multi module command line) {
for (each module you have to execute) {
main(new String[] {"-startModule1", ..., ...}); // call myself with different args
}
}
else {
// execute what you've been asked for
}
}
I've got a java code that is writing a Linux bash script out, then doing a chmod to add execute permission, then trying to execute it. I'm getting an IOException during the start of the process saying error=26, Text file busy. I've verified that the file is finished being written and the stream was closed. The chmod works fine, but I keep getting this error.
I've noticed that if I run a debugger and step through the code, it doesn't get the error, so clearly there is a timing issue involved. How can I make sure the chmod is done before I try to execute the bash script? I'd like to avoid non-reliable solutions like adding Thread.sleep(10000), and "hacky" things like putting the execution in a try/catch block inside a loop that tries until it succeeds.
I have a fair amount of code wrapping the startup of the process with listening threads, etc., but here is a simplified version of what it is doing (tried this code also and it has same result):
String[] cmd1 = {"/bin/chmod", "750", postFile };
new ProcessBuilder(cmd1).redirectErrorStream(true).start().waitFor();
String[] cmd2 = { postFile };
new ProcessBuilder(cmd2).redirectErrorStream(true).start().waitFor();
Every time after execution, the "postFile" has the correct 750 permissions, but it has not executed (due to the IOException).
For future reference, it may have been caused by an unclosed stream in this particular case, but setting permissions on a file immediately followed by running the file can cause this error too:
java.io.IOException: Cannot run program "...": error=26, Text file busy
It is a probable bug in JDK. In my case, it was caused by this snippet of code
Files.setPosixFilePermissions(Paths.get(scriptPath), set(PosixFilePermission.OWNER_EXECUTE, PosixFilePermission.OWNER_READ));
ProcessBuilder processBuilder = new ProcessBuilder(scriptPath).directory(workingDir);
processBuilder.start();
even if nothing was editing the script file.
Are you sure it is the chmod that is responsible for the subsequent error? Could you check that you definitely close the output file before you try to run it?
If you do close it then I'm at a loss why chmod should cause that error, but you could avoid the need to run chmod by using your shell to run the script:
String[] cmd = {"bash", postfile };
I don't know if it's related but usually you need to get or redirect the ErrorStream and the InputStream (I usually get them in a ResponseStreamReader that I create, don't know about the redirecting choice).
In my service file in /etc/systemd/system/ I have directed outputs to log files:
StandardOutput=file:/home/pi/ApplicationLogs/application_l_debug.log
StandardError=file:/home/pi/ApplicationLogs/application_l_error.log
The error message disappeared when I changed permissions on the ApplicationLogs directory to write permissions to all
(chmod a+w ApplicationLogs)
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
?>
I use the Eclipse IDE to develop, compile, and run my Java projects. Today, I'm trying to use the java.io.Console class to manage output and, more importantly, user input.
The problem is that System.console() returns null when an application is run "through" Eclipse. Eclipse run the program on a background process, rather than a top-level process with the console window we're familiar with.
Is there a way to force Eclipse to run the program as a top level process, or at least create a Console that the JVM will recognize? Otherwise, I'm forced to jar the project up and run on a command-line environment external to Eclipse.
I assume you want to be able to use step-through debugging from Eclipse. You can just run the classes externally by setting the built classes in the bin directories on the JRE classpath.
java -cp workspace\p1\bin;workspace\p2\bin foo.Main
You can debug using the remote debugger and taking advantage of the class files built in your project.
In this example, the Eclipse project structure looks like this:
workspace\project\
\.classpath
\.project
\debug.bat
\bin\Main.class
\src\Main.java
1. Start the JVM Console in Debug Mode
debug.bat is a Windows batch file that should be run externally from a cmd.exe console.
#ECHO OFF
SET A_PORT=8787
SET A_DBG=-Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,address=%A_PORT%,server=y,suspend=y
java.exe %A_DBG% -cp .\bin Main
In the arguments, the debug port has been set to 8787. The suspend=y argument tells the JVM to wait until the debugger attaches.
2. Create a Debug Launch Configuration
In Eclipse, open the Debug dialog (Run > Open Debug Dialog...) and create a new Remote Java Application configuration with the following settings:
Project: your project name
Connection Type: Standard (Socket Attach)
Host: localhost
Port: 8787
3. Debugging
So, all you have to do any time you want to debug the app is:
set a break point
launch the batch file in a console
launch the debug configuration
You can track this issue in bug 122429. You can work round this issue in your application by using an abstraction layer as described here.
The workaround that I use is to just use System.in/System.out instead of Console when using Eclipse. For example, instead of:
String line = System.console().readLine();
You can use:
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
String line = bufferedReader.readLine();
The reason this occurs is because eclipse runs your app as a background process and not as a top-level process with a system console.
You can implement a class yourself. Following is an example:
public class Console {
BufferedReader br;
PrintStream ps;
public Console(){
br = new BufferedReader(new InputStreamReader(System.in));
ps = System.out;
}
public String readLine(String out){
ps.format(out);
try{
return br.readLine();
}catch(IOException e)
{
return null;
}
}
public PrintStream format(String format, Object...objects){
return ps.format(format, objects);
}
}
Found something about this at http://www.stupidjavatricks.com/?p=43 .
And sadly, since console is final, you can't extend it to create a a wrapper around system.in and system.out that does it either. Even inside the eclipse console you still have access to those. Thats probably why eclipse hasn't plugged this into their console yet...
I understand why you wouldn't want to have any other way to get a console other than System.console, with no setter, but i don't understand why you wouldn't want someone to be able to override the class to make a mock/testing console...
Another option is to create a method to wrap up both options, and "fail over" to the System.in method when Console isn't available. The below example is a fairly basic one - you can follow the same process to wrap up the other methods in Console (readPassword, format) as required. That way you can run it happily in Eclipse & when its deployed you get the Console features (e.g. password hiding) kicking in.
private static String readLine(String prompt) {
String line = null;
Console c = System.console();
if (c != null) {
line = c.readLine(prompt);
} else {
System.out.print(prompt);
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
try {
line = bufferedReader.readLine();
} catch (IOException e) {
//Ignore
}
}
return line;
}
As far as I can tell, there is no way to get a Console object from Eclipse. I'd just make sure that console != null, then JAR it up and run it from the command line.
There seems to be no way to get a java.io.Console object when running an application through Eclipse. A command-line console window is not opened with the application, as it is run as a background process (background to Eclipse?). Currently, there is no Eclipse plugin to handle this issue, mainly due to the fact that java.io.Console is a final class.
All you can really do is test the returned Console object for null and proceed from there.
This link offers alternatives to using System.console(). One is to use a BufferedReader wrapped around System.in, the second is to use a Scanner wrapped around System.in.
Neither are as concise as console, but both work in eclipse without having to resort to debug silliness!
Let's say your Eclipse workspace is C:\MyWorkspace,
you created your java application inside a maven project MyProject,
and your Java main class is com.mydomain.mypackage.MyClass.
In this case, you can run your main class that uses System.console() on the command line:
java -cp C:\MyWorkspace\MyProject\target\classes com.mydomain.mypackage.MyClass
NB1: if it's not in a maven project, check the output folder in project properties | Java Build Path | Source. It might not be "target/classes"
NB2: if it is a maven project, but your class is in src/test/java, you'll likely have to use "target\test-classes" instead of "target\classes"