I am using the sshj library for java.
I need to open an ssh session on a remote server, execute a command which could run for many minutes, and then continue on executing in my java code. Once the command running on the remote server is finished, i would like the ssh session to close, and the sshclient to disconnect.
I have seen the following code example:
public class Exec {
public static void main(String... args) throws IOException {
final SSHClient ssh = new SSHClient();
ssh.loadKnownHosts();
ssh.connect("localhost");
try {
ssh.authPublickey(System.getProperty("user.name"));
final Session session = ssh.startSession();
try {
final Command cmd = session.exec("ping -c 1 google.com");
System.out.println(IOUtils.readFully(cmd.getInputStream()).toString());
cmd.join(5, TimeUnit.SECONDS);
System.out.println("\n** exit status: " + cmd.getExitStatus());
} finally {
session.close();
}
} finally {
ssh.disconnect();
}
}
}
Basically I don't want to wait for the command to finish (no cmd.join call) and I need the session.close() and ssh.disconnect() to be called automatically once the command has exited. Is this possible?
I may not be able to exactly answer my question, but maybe provide help for others trying to do something similar to what I was doing. When I posted, I was under the impression that the ssh session had to stay open for the command to finish, but I don't think that is the case.
So what I was trying to do was start a remote ssh session via java, and run a shell script on the remote machine. The shell script could take up to 10-15 mins to complete. I tested a short timeout (5 secs) and the script continued to run after the session was disconnected... which is what I wanted.
Related
I am currently working on a java automation application incorporating Jsch. When I run my code however, it passes back an error saying that the TERM environment is not set up.
I already tried to manually add the environment in intellij by choosing environment variables. Then I add TERM=xterm. Though when I run that, it still fails.
import com.jcraft.jsch.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
public class Driver {
public static void main(String[] args) throws Exception {
JSch jsch = new JSch();
Session session;
try {
// Open a Session to remote SSH server and Connect.
// Set User and IP of the remote host and SSH port.
session = jsch.getSession("username", "host", 22);
// When we do SSH to a remote host for the 1st time or if key at the remote host
// changes, we will be prompted to confirm the authenticity of remote host.
// This check feature is controlled by StrictHostKeyChecking ssh parameter.
// By default StrictHostKeyChecking is set to yes as a security measure.
session.setConfig("StrictHostKeyChecking", "no");
//Set password
session.setPassword("password");
session.connect();
// create the execution channel over the session
ChannelExec channelExec = (ChannelExec) session.openChannel("exec");
// Set the command to execute on the channel and execute the command
channelExec.setCommand("./script.sh");
channelExec.connect();
// Get an InputStream from this channel and read messages, generated
// by the executing command, from the remote side.
InputStream in = channelExec.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
// Command execution completed here.
// Retrieve the exit status of the executed command
int exitStatus = channelExec.getExitStatus();
if (exitStatus > 0) {
System.out.println("Remote script exec error! " + exitStatus);
}
//Disconnect the Session
session.disconnect();
} catch (JSchException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Make sure that the variable is set in your current shell by either exporting it or running your code with a set variable for TERM.
Something similar to the following should work:
TERM=linux /path/to/your/executable --some-arguments
The following could possibly only be relevant to bash but there is also a way to export a variable so as to make it global.
After exporting a variable, you can verify its value using:
echo $TERM
Empty response means variable is not set. Else, well... you get it i am sure. In order to export it globally, in bash that is, you can use the command line directly or add the export command into your dotfiles, which should be loaded upon login
export TERM=linux
Either way you choose, the command stays the same. There are multiple terminals and types, 'linux' being a very very generic one. A more color-friendly solution could be to try using 'xterm-256color' instead.
export TERM=xterm-256color
You should check out the basics of terminal if you wish to learn more. I hope this can help you achive your desired outcome.
Cheers
IntelliJ IDEA Run console is not a real Terminal, hence the problem.
You can run the code manually outside of IntelliJ IDEA or in the Terminal tool window.
For debugging you can use the Remote debug.
Related request: Add option to run configuration to launch in real console.
I have a piece of code which connects to a Unix server and executes commands.
I have been trying with simple commands and they work fine.
I am able to login and get the output of the commands.
I need to run an Ab-initio graph through Java.
I am using the air sandbox run graph command for this.
It runs fine, when I login using SSH client and run the command. I am able to run the graph. However, when I try to run the command through Java it gives me a "air not found" error.
Is there any kind of limit on what kind of Unix commands JSch supports?
Any idea why I'm not able to run the command through my Java code?
Here's the code:
public static void connect(){
try{
JSch jsch=new JSch();
String host="*****";
String user="*****";
String config =
"Host foo\n"+
" User "+user+"\n"+
" Hostname "+host+"\n";
ConfigRepository configRepository =
com.jcraft.jsch.OpenSSHConfig.parse(config);
jsch.setConfigRepository(configRepository);
Session session=jsch.getSession("foo");
String passwd ="*****";
session.setPassword(passwd);
UserInfo ui = new MyUserInfo(){
public boolean promptYesNo(String message){
int foo = 0;
return foo==0;
}
};
session.setUserInfo(ui);
session.connect();
String command="air sandbox run <graph-path>";
Channel channel=session.openChannel("exec");
((ChannelExec)channel).setCommand(command);
channel.setInputStream(null);
((ChannelExec)channel).setErrStream(System.err);
InputStream in=channel.getInputStream();
channel.connect();
byte[] tmp=new byte[1024];
while(true){
while(in.available()>0){
int i=in.read(tmp, 0, 1024);
if(i<0)break;
page_message=new String(tmp, 0, i);
System.out.print(page_message);
}
if(channel.isClosed()){
if(in.available()>0) continue;
System.out.println("exit-status: "+channel.getExitStatus());
break;
}
try{Thread.sleep(1000);}catch(Exception ee){}
}
channel.disconnect();
session.disconnect();
}
catch(Exception e){
System.out.println(e);
}
}
public static void main(String arg[]){
connect();
}
public String return_message(){
String ret_message=page_message;
return ret_message;
}
public static abstract class MyUserInfo
implements UserInfo, UIKeyboardInteractive{
public String getPassword(){ return null; }
public boolean promptYesNo(String str){ return false; }
public String getPassphrase(){ return null; }
public boolean promptPassphrase(String message){ return false; }
public boolean promptPassword(String message){ return false; }
public void showMessage(String message){ }
public String[] promptKeyboardInteractive(String destination,
String name,
String instruction,
String[] prompt,
boolean[] echo){
return null;
}
}
The "exec" channel in the JSch (rightfully) does not allocate a pseudo terminal (PTY) for the session. As a consequence a different set of startup scripts is (might be) sourced (particularly for non-interactive sessions, .bash_profile is not sourced). And/or different branches in the scripts are taken, based on absence/presence of the TERM environment variable. So the environment might differ from the interactive session, you use with your SSH client.
So, in your case, the PATH is probably set differently; and consequently the air executable cannot be found.
To verify that this is the root cause, disable the pseudo terminal allocation in your SSH client. For example in PuTTY, it's Connection > SSH > TTY > Don't allocate a pseudo terminal. Then, go to Connection > SSH > Remote command and enter your air ... command. Check Session > Close window on exit > Never and open the session. You should get the same "air not found" error.
Ways to fix this, in preference order:
Fix the command not to rely on a specific environment. Use a full path to air in the command. E.g.:
/bin/air sandbox run <graph-path>
If you do not know the full path, on common *nix systems, you can use which air command in your interactive SSH session.
Fix your startup scripts to set the PATH the same for both interactive and non-interactive sessions.
Try running the script explicitly via login shell (use --login switch with common *nix shells):
bash --login -c "air sandbox run sandbox run <graph-path>"
If the command itself relies on a specific environment setup and you cannot fix the startup scripts, you can change the environment in the command itself. Syntax for that depends on the remote system and/or the shell. In common *nix systems, this works:
String command="PATH=\"$PATH;/path/to/air\" && air sandbox run <graph-path>";
Another (not recommended) approach is to force the pseudo terminal allocation for the "exec" channel using the .setPty method:
Channel channel = session.openChannel("exec");
((ChannelExec)channel).setPty(true);
Using the pseudo terminal to automate a command execution can bring you nasty side effects. See for example Is there a simple way to get rid of junk values that come when you SSH using Python's Paramiko library and fetch output from CLI of a remote machine?
For a similar issues, see
Certain Unix commands fail with "... not found", when executed through Java using JSch even with setPty enabled
Commands executed using JSch behaves differently than in SSH terminal (bypasses confirm prompt message of "yes/"no")
JSch: Is there a way to expose user environment variables to "exec" channel?
Command (.4gl) executed with SSH.NET SshClient.RunCommand fails with "No such file or directory"
you could try to find out where "air" resides with
whereis air
and then use this outcome.
something like
/usr/bin/air sandbox run graph
You can use an ~/.ssh/environment file to set your AB_HOME and PATH variables.
I have a piece of code which connects to a Unix server and executes commands.
I have been trying with simple commands and they work fine.
I am able to login and get the output of the commands.
I need to run an Ab-initio graph through Java.
I am using the air sandbox run graph command for this.
It runs fine, when I login using SSH client and run the command. I am able to run the graph. However, when I try to run the command through Java it gives me a "air not found" error.
Is there any kind of limit on what kind of Unix commands JSch supports?
Any idea why I'm not able to run the command through my Java code?
Here's the code:
public static void connect(){
try{
JSch jsch=new JSch();
String host="*****";
String user="*****";
String config =
"Host foo\n"+
" User "+user+"\n"+
" Hostname "+host+"\n";
ConfigRepository configRepository =
com.jcraft.jsch.OpenSSHConfig.parse(config);
jsch.setConfigRepository(configRepository);
Session session=jsch.getSession("foo");
String passwd ="*****";
session.setPassword(passwd);
UserInfo ui = new MyUserInfo(){
public boolean promptYesNo(String message){
int foo = 0;
return foo==0;
}
};
session.setUserInfo(ui);
session.connect();
String command="air sandbox run <graph-path>";
Channel channel=session.openChannel("exec");
((ChannelExec)channel).setCommand(command);
channel.setInputStream(null);
((ChannelExec)channel).setErrStream(System.err);
InputStream in=channel.getInputStream();
channel.connect();
byte[] tmp=new byte[1024];
while(true){
while(in.available()>0){
int i=in.read(tmp, 0, 1024);
if(i<0)break;
page_message=new String(tmp, 0, i);
System.out.print(page_message);
}
if(channel.isClosed()){
if(in.available()>0) continue;
System.out.println("exit-status: "+channel.getExitStatus());
break;
}
try{Thread.sleep(1000);}catch(Exception ee){}
}
channel.disconnect();
session.disconnect();
}
catch(Exception e){
System.out.println(e);
}
}
public static void main(String arg[]){
connect();
}
public String return_message(){
String ret_message=page_message;
return ret_message;
}
public static abstract class MyUserInfo
implements UserInfo, UIKeyboardInteractive{
public String getPassword(){ return null; }
public boolean promptYesNo(String str){ return false; }
public String getPassphrase(){ return null; }
public boolean promptPassphrase(String message){ return false; }
public boolean promptPassword(String message){ return false; }
public void showMessage(String message){ }
public String[] promptKeyboardInteractive(String destination,
String name,
String instruction,
String[] prompt,
boolean[] echo){
return null;
}
}
The "exec" channel in the JSch (rightfully) does not allocate a pseudo terminal (PTY) for the session. As a consequence a different set of startup scripts is (might be) sourced (particularly for non-interactive sessions, .bash_profile is not sourced). And/or different branches in the scripts are taken, based on absence/presence of the TERM environment variable. So the environment might differ from the interactive session, you use with your SSH client.
So, in your case, the PATH is probably set differently; and consequently the air executable cannot be found.
To verify that this is the root cause, disable the pseudo terminal allocation in your SSH client. For example in PuTTY, it's Connection > SSH > TTY > Don't allocate a pseudo terminal. Then, go to Connection > SSH > Remote command and enter your air ... command. Check Session > Close window on exit > Never and open the session. You should get the same "air not found" error.
Ways to fix this, in preference order:
Fix the command not to rely on a specific environment. Use a full path to air in the command. E.g.:
/bin/air sandbox run <graph-path>
If you do not know the full path, on common *nix systems, you can use which air command in your interactive SSH session.
Fix your startup scripts to set the PATH the same for both interactive and non-interactive sessions.
Try running the script explicitly via login shell (use --login switch with common *nix shells):
bash --login -c "air sandbox run sandbox run <graph-path>"
If the command itself relies on a specific environment setup and you cannot fix the startup scripts, you can change the environment in the command itself. Syntax for that depends on the remote system and/or the shell. In common *nix systems, this works:
String command="PATH=\"$PATH;/path/to/air\" && air sandbox run <graph-path>";
Another (not recommended) approach is to force the pseudo terminal allocation for the "exec" channel using the .setPty method:
Channel channel = session.openChannel("exec");
((ChannelExec)channel).setPty(true);
Using the pseudo terminal to automate a command execution can bring you nasty side effects. See for example Is there a simple way to get rid of junk values that come when you SSH using Python's Paramiko library and fetch output from CLI of a remote machine?
For a similar issues, see
Certain Unix commands fail with "... not found", when executed through Java using JSch even with setPty enabled
Commands executed using JSch behaves differently than in SSH terminal (bypasses confirm prompt message of "yes/"no")
JSch: Is there a way to expose user environment variables to "exec" channel?
Command (.4gl) executed with SSH.NET SshClient.RunCommand fails with "No such file or directory"
you could try to find out where "air" resides with
whereis air
and then use this outcome.
something like
/usr/bin/air sandbox run graph
You can use an ~/.ssh/environment file to set your AB_HOME and PATH variables.
Im using sshj and im trying to tail a file, but my problem is that the remote process is never killed.
In the following example code you can see that i try to tail /var/log/syslog, and then i send a kill signal to the process. However after the application has stopped and i list out all the processes on the server, i can still see an active tail process.
Why will not this code kill the process? and what can i do to remedy that?
SSHClient ssh = new SSHClient();
ssh.addHostKeyVerifier(new PromiscuousVerifier());
try {
ssh.connect("localhost");
ssh.authPassword("xxx", "xxx");
final Session session = ssh.startSession();
try {
final Command cmd = session.exec("tail -f /var/log/syslog");
cmd.signal(Signal.KILL);
System.out.println("\n** exit status: " + cmd.getExitStatus());
} catch (IOException e) {
e.printStackTrace();
}finally{
session.close();
}
} finally{
ssh.disconnect();
}
EDIT
also tried sending all available signals.
for(Signal s : Signal.values()){
cmd.signal(s);
}
Allocating a PTY and sending a Ctrl+C character code did the trick for me:
final Session session = ssh.startSession();
session.allocateDefaultPTY();
try {
final Command cmd = session.exec("tail -f /var/log/syslog");
// Send Ctrl+C (character code is 0x03):
cmd.getOutputStream().write(3);
cmd.getOutputStream().flush();
// Wait some time for the process to exit:
cmd.join(1, TimeUnit.SECONDS);
// If no exception has been raised yet, then the process has exited
// (but the exit status can still be null if the process has been killed).
System.out.println("\n** exit status: " + cmd.getExitStatus());
} catch (IOException e) {
e.printStackTrace();
}finally{
session.close();
}
Of course, being able to send signals would be better, but if even the OpenSSH server does not support it, there's no hope there :/
openssh doesn't support it https://bugzilla.mindrot.org/show_bug.cgi?id=1424
Just use cmd.close(), that should term the process as well
This is most likely a problem with the ssh server implementation, as i have tried using two different ssh clients and getting the same result. My solution ended up being a client-side tail logic, instead of "tail -f" to prevent free roaming processes.
Had a similar issue recently. In my specific case it was the OpenSSH issue mentioned by #shikhar.
My solution was to run start another session (sharing the connection) and run a kill command pgrep mycommand | xargs kill.
I am new to Selenium. I generated my first java selenium test case and it has compiled successfully. But when I run that test I got the following RuntimeException
java.lang.RuntimeException: Could not start Selenium session: Failed to start new browser session: Error while launching browser at com.thoughtworks.selenium.DefaultSelenium.start <DefaultSelenium.java:88>
Kindly tell me how can I fix this error.
This is the java file I want to run.
import com.thoughtworks.selenium.*;
import java.util.regex.Pattern;
import junit.framework.*;
public class orkut extends SeleneseTestCase {
public void setUp() throws Exception {
setUp("https://www.google.com/", "*chrome");
}
public void testOrkut() throws Exception {
selenium.setTimeout("10000");
selenium.open("/accounts/ServiceLogin?service=orkut&hl=en-US&rm=false&continue=http%3A%2F%2Fwww.orkut.com%2FRedirLogin%3Fmsg%3D0&cd=IN&skipvpage=true&sendvemail=false");
selenium.type("Email", "username");
selenium.type("Passwd", "password");
selenium.click("signIn");
selenium.selectFrame("orkutFrame");
selenium.click("link=Communities");
selenium.waitForPageToLoad("10000");
}
public static Test suite() {
return new TestSuite(orkut.class);
}
public void tearDown(){
selenium.stop();
}
public static void main(String args[]) {
junit.textui.TestRunner.run(suite());
}
}
I first started the selenium server through the command prompt and then execute the above java file through another command prompt.
Second Question: Can I do right click on a specified place on a webpage with selenium.
Chances are this problem is caused by an already-running instance of the Selenium server. The new instance needs to listen on the same port number, but can't, because the port is already in use.
Let's say your Selenium server is configured to start on port 4444. Determine if the port is in use using the 'netstat' command:
On Windows: netstat -an | find "4444"
Expect to see output like this:
TCP 0.0.0.0:4444 0.0.0.0:0 LISTENING
TCP [::]:4444 [::]:0 LISTENING
On Linux, use: netstat -anp | grep 4444
(No Linux box to hand, so can't show example output!)
If you see any output, you need to kill the process that's listening on the port that Selenium wants to use. On Windows, use netstat -anb to find the process name (it'll be listed after the line specifying the port number). Kill it using the Task Manager. On Linux, the process PID and name will be listed by the command above - kill it using kill <PID>.
If you're using the last version of Selenium RC (after 1.0) you should change the following:
setUp("https://www.google.com/", "*chrome");
for
setUp("https://www.google.com/", "*firefox");
If this doesn't work, try creating a separate firefox profile and using that one:
http://seleniumhq.org/docs/05_selenium_rc.html#specifying-the-firefox-profile
I know this might sound silly but are you sure you have given selenium.start() in your code? Beginners can make this mistake.
Always make sure, selenium.stop() method has been called at the end of test steps.
The setUp method basically invokes start method, so don't need to give selenium.start() in above code. I guess this is kind of selenium's bug. it stops testing before it get some response. but I've not found why yet.