[英]Jsch - One Session Multiple Channels
I managed to execute a single command through ssh with Jsch but when i try to execute a second command it fails 我设法通过ssh用Jsch执行单个命令但是当我尝试执行第二个命令时它失败了
For debugging i brought this problem down to this lines: 为了调试我把这个问题归结为这样:
import java.io.IOException;
import java.io.InputStream;
import com.jcraft.jsch.Channel;
import com.jcraft.jsch.ChannelExec;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;
public class Exec {
public static void test(Session session) throws Exception {
Channel channel = session.openChannel("exec");
((ChannelExec) channel).setCommand("pwd");
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;
System.out.print(new String(tmp, 0, i));
}
if (channel.isClosed()) {
System.out.println("exit-status: " + channel.getExitStatus());
break;
}
try {
Thread.sleep(1000);
} catch (Exception ee) {
}
}
channel.disconnect();
}
public static void main(String[] arg) {
try {
JSch jsch = new JSch();
Session session = jsch.getSession("nck", "127.0.0.1", 22);
session.setPassword("asd");
session.setConfig("StrictHostKeyChecking", "no");
session.connect();
test(session); // This one succeeds with exit-status: 0
test(session); // This one fails with exit-status: 255
session.disconnect();
} catch (Exception e) {
//
}
}
}
This is mostly the official Exec example but this gives me this output: 这主要是官方的Exec示例,但这给了我这个输出:
/home/nck
exit-status: 0
exit-status: 255
The first command is executed succesfully the second doesnt. 第一个命令成功执行第二个不执行。
Any Ideas ? 有任何想法吗 ?
Here is a complete working Java class based on @krishna's answer: 这是一个基于@krishna答案的完整的Java类:
/**
* Run several ssh commands in a single JSch session
*/
import com.jcraft.jsch.Channel;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;
import java.io.*;
class SshMultiCommands
{
public static void main(String[] args) throws Exception
{
JSch jsch = new JSch();
String user = "user"; //CHANGE ME
String host = "192.168.222.157"; //CHANGE ME
String passwd = "password"; //CHANGE ME
int port = 22;
Session session = jsch.getSession(user, host, port);
session.setPassword(passwd);
session.setConfig("StrictHostKeyChecking", "no");
session.connect();
Channel channel = session.openChannel("shell");
OutputStream ops = channel.getOutputStream();
PrintStream ps = new PrintStream(ops, true);
channel.connect();
InputStream input = channel.getInputStream();
//commands
ps.println("ls -lag");
ps.println("cd /etc");
ps.println("ls");
ps.println("exit");
ps.close();
printResult(input, channel);
channel.disconnect();
session.disconnect();
}
/**
* @param input
* @param channel
*/
private static void printResult(InputStream input,
Channel channel) throws Exception
{
int SIZE = 1024;
byte[] tmp = new byte[SIZE];
while (true)
{
while (input.available() > 0)
{
int i = input.read(tmp, 0, SIZE);
if(i < 0)
break;
System.out.print(new String(tmp, 0, i));
}
if(channel.isClosed())
{
System.out.println("exit-status: " + channel.getExitStatus());
break;
}
try
{
Thread.sleep(300);
}
catch (Exception ee)
{
}
}
}
}
Hey I have exactly the same problem with jsch and Ubuntu. 嘿我和jsch和Ubuntu有完全相同的问题。 (How) did you solve it?
(怎么样)你解决了吗? Making a new session for every execute eats too much time?
为每次执行创建一个新会话会占用太多时间吗? At the moment I catch the jsch exception and search for "session isn't down" then I reconnect the session and execute command again.
目前我捕获了jsch异常并搜索“session is not down”然后我重新连接会话并再次执行命令。 That works but is not a good solution.
这有效,但不是一个好的解决方案。
Edit: I was on the wrong way I solved my problem for now by using 编辑:我错了,我现在通过使用解决了我的问题
channel = session.openChannel("shell");
instead of "exec". 而不是“exec”。
you can use shell to execute multiple commands. 你可以使用shell来执行多个命令。 following is the code to execute commands via shell.
以下是通过shell执行命令的代码。
Channel channel=session.openChannel("shell");
OutputStream ops = channel.getOutputStream();
PrintStream ps = new PrintStream(ops, true);
channel.connect();
ps.println("mkdir folder");
ps.println("dir");
//give commands to be executed inside println.and can have any no of commands sent.
ps.close();
InputStream in=channel.getInputStream();
byte[] bt=new byte[1024];
while(true) {
while(in.available()>0) {
int i=in.read(bt, 0, 1024);
if(i<0)
break;
String str=new String(bt, 0, i);
//displays the output of the command executed.
System.out.print(str);
}
if(channel.isClosed())
break;
Thread.sleep(1000);
channel.disconnect();
session.disconnect();
}
I used exactly same code and had problem some of the times reading output of the script i executed through ssh. 我使用完全相同的代码,并且有时会读取通过ssh执行的脚本输出的问题。 Sometimes the program was missing the all content, and sometime only a part of the content.
有时程序缺少所有内容,有时只缺少部分内容。 I resolved my problem by changing the if(channel.isclosed) in the nested loop.
我通过更改嵌套循环中的if(channel.isclosed)解决了我的问题。 Here is the new code
这是新代码
while (true) {
while (in.available() > 0) {
int i = in.read(tmp, 0, 1024);
if (i < 0)
break;
System.out.print(new String(tmp, 0, i));
}
if (channel.isClosed()) {
if(in.available() > 0) {
int i = in.read(tmp, 0, 1024);
System.out.print(new String(tmp, 0, i));
}
System.out.println("exit-status: " + channel.getExitStatus());
break;
}
try {
Thread.sleep(1000);
} catch (Exception ee) {
}
If you want to use exec. 如果你想使用exec。 you can run multiple commands by putting a semi colon (;) within commands
您可以通过在命令中放置一个分号(;)来运行多个命令
like: 喜欢:
pwd;ls- -l;
cd foldername
((ChannelExec) channel).setCommand("pwd;ls -l; cd foldername");
This wasn't a bug in jsch, it was a bug of my ssh server (cygwin - I bet I configured something wrong...) 这不是jsch中的错误,它是我的ssh服务器的一个错误(cygwin - 我打赌我配置错了......)
Edit: hmm I had the same problem with jsch with Ubuntu ... weird 编辑:嗯我与Ubuntu的jsch有同样的问题......很奇怪
Guess as workarround I'll have to open a new session for each query. 猜测是workarround我将不得不为每个查询打开一个新的会话。
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