Accessing OS level commands through Java?

Hello everyone,
Is it possible to access OS-level (Unix BSD for instance) commands through Java classes or methods?
"OS-level commands" refers strictly to Unix commands such as I/O CTL (control), Poll and Select through a file descriptor.
"Access" refers to legitimate, built-in OR illegitimate (forced by "fooling" the system) access.

However, the calls that you refer to, have been implemented in java; that goes for read/write/select (java.io and java.nio). But they pass through the java api implementation, and then throught the native implementation inside the JVM. If you want to use the raw power of poll() through java, you'd have to implement it yourself in JNI. But even if you successfully implement that, you must always remember that you'd have to make corresponding java classes that serve as arguments to your call, which, inside C, you must unpack again - so there goes your speed-advantage out the window.

Similar Messages

Problem in executing a unix command through java

hi
i'm trying to execute unix command through java
simple shell command like "ls -l >test " but i'm not able to see the result.
there are no error messages.
Code is:
import java.lang.Runtime.*;
class ExecDemo
     public static void main(String[] args)
          Runtime r=Runtime.getRuntime();
          Process p=null;
          try
               p=r.exec("ls -l > test");
          catch (Exception e)
               System.out.println("Error executing nedit.");
}can anyone help please.

get the the inputStream of the runtime object after executing the command.
now use the readLine() function until it becomes null.
egs: with reference to ur code.
InputStream is=p.getInputStream()
while(is!=null)
String s=is.readLine();
if the command don't execute try giving the full path also like /sbin/ls -l

Running cmd commands through java

Hi,
I am trying to run few dos commands through java using Runtime.exec("command") but I am getting following error
commmand is cd D:\CodeMerge\A\
java.io.IOException: CreateProcess: cd.. error=2
at java.lang.Win32Process.create(Native Method)
at java.lang.Win32Process.<init>(Unknown Source)
at java.lang.Runtime.execInternal(Native Method)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at createDirectory.main(createDirectory.java:24)
Basically what I am looking for is this:
1) My program is in D:\Amit\RM
2) I want to get out to D:\ go to CodeMerge\A\.
3) Create folder with curretn date as name of the folder
Hence I am doing
rTime.exec("cd../..");
rTime.exec("cd D:\CodeMerge\A\");
rTime.exec("mkdir "+date);
Can anybody tell me why I am getting this error
Jounty

U can run either DOS Commands or UNIX Commands thru the following Java Program
Written By BalaNagaraju Malisetti
contact: [email protected]
import java.io.*;
public class RunBdiff
public static String rununixcmd(String v_prev_path,String v_curr_path,String v_delta_path,String v_beg,String v_len)
String s = null;
FileOutputStream fos;
DataOutputStream dos;
try
int v_int_beg = Integer.parseInt(v_beg);
int v_int_len=Integer.parseInt(v_len);
int v_int_end=(v_int_beg+v_int_len)-1;
String v_pos1=String.valueOf((v_int_beg+2));
String v_pos2=String.valueOf((v_int_end+2));
String cmd1 = "bdiff ";
String cmd2=v_prev_path;
String cmd3=" ";
String cmd4=v_curr_path;
String cmd5="| grep '^>'";
String cmd6="| cut -c";
String cmd7=v_pos1+"-"+v_pos2;
String cmd8="| sort ";
String cmd9="| uniq ";
String cmd=cmd1+cmd2+cmd3+cmd4+cmd5+cmd6+cmd7+cmd8+cmd9;
String[] commands = {"/bin/csh","-c",cmd}; //in Unix
//String[] commands = {"cmd.exe","-c",cmd}; //in Windows
Process p = Runtime.getRuntime().exec(commands);
BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));
// read the output from the command
File file = new File(v_delta_path);
fos = new FileOutputStream(file);
dos=new DataOutputStream(fos);
//Writing the output of bdiff command to Delta File
while ((s = stdInput.readLine()) != null)
dos.writeChars(s);
//Return Error Message to Calling Procedure
while ((s = stdError.readLine()) != null)
return s;
return s;
catch (IOException e)
return String.valueOf(e);
public static void main(String args[])
String msg=rununixcmd("/home/g_anil/MS_ADDRESS1.dat","/home/g_anil/MS_ADDRESS2.dat","/home/g_anil/MS_ADDRESS_DELTA.dat","1","9");
**************************************************************************************************************************************

What is the best way to call SSH commands through Java technologies

What is the best way to call SSH commands through Java technologies

I don't think you can specify the password at the prompt using ssh. Plink has the -pw command option for passwords. What I did was except ssh to ask me and write the password programmatically through the outputStream I obtained from my Process object. I looked for "password: ", and then wrote the password with a trailing newline.
Both plink and ssh will also ask if you trust the host if it is the first time you are connecting to it. So before just writing the password, check if the program wants verification from you: normally supplying "y" or "n". This should only have to happen the first time the client connects. It looks like thisPLINK:
The server's host key is not cached in the registry. You
have no guarantee that the server is the computer you
think it is.
The server's key fingerprint is:
1024 f8:43:61:4c:a2:5b:77:be:5b:a7:bb:1f:f7:79:b3:b7
If you trust this host, enter "y" to add the key to
PuTTY's cache and carry on connecting.
If you want to carry on connecting just once, without
adding the key to the cache, enter "n".
If you do not trust this host, press Return to abandon the
connection.
Store key in cache? (y/n)
SSH:
The authenticity of host '127.0.0.1 (127.0.0.1)' can't be established.
RSA key fingerprint is e1:02:13:c8:52:c2:23:41:9b:5b:58:2c:18:e6:59:af.
Are you sure you want to continue connecting (yes/no)?What I did was read character by character from the inputStream until I found things of interest ... like "password: ". You only need to search for this in your method which will launch the ssh or plink Process. Once you have verifyed yourself, you can just pass commands to the Process, which is an ssh connection.
My suggestion is to read() each byte from the Process's inputStream and write it to stdout. Look and see what you need to be looking for so you can interactive with the program correctly. You can't use readLine here becuase when the ssh asks for the password it does not print a newline. I do know for sure, that ssh will simply print, "passowrd: ". Plink will print this as well if the -pw option is not supplied.

Execute dos commands through java

Hi,
Im trying to execute dos commands through java like
          try {
               java.lang.Runtime.getRuntime().exec("cmd /c cls");
          }catch(IOException e){
               System.out.println(e.getMessage());
          }Not sure if its possible? however
open notepad would work
          try {
               java.lang.Runtime.getRuntime().exec("notepad");
          }catch(IOException e){
               System.out.println(e.getMessage());
          }Im trying to execute a cls commands to clear screen but without luck.

The question is, which shell do you want to clear?
I don't really know, but it could be that Runtime.exec executes its command in a new shell window...

Running Unix command through Java

Hi
I am trying to run the unix command "rf filename" through Java and it doesnt seem to work.
Can anyone help in this case please
String cm = "rm ";
String delFile = args[0]; // this path is /data/temp/filename.doc
Process p = Runtime.getRuntime.exec(cmd +delFile);Also since i dont have access to delete the file through my login i always login as root for a few commands.
Is there a way i can specify user name & password & then run the command?
Please let me know
Thanx

Please discard the above msg i got a solution by just adding file.delete
thanx

PI 7.1 Access to Dynamic Configuration through Java Class

My Current scenario involves IDCO -> FILE communications in PI 7.1 using XSL where the file name is dynamic.
I have attempted calling a Java Class from XSL with the use SAPXMLTOOL kit option set in the adaptor and it works but I need to be able to call the transform method
public void transform(TransformationInput arg0, TransformationOutput arg1)
from XSL so I can access the message and update the File Name via Dynamic Configuration.
Whilst I can call a static class with in the object I can not call transform with the correct arguments (arg0, arg1). I need access to arg0 (payload) to set/figure out the filename. I can calculate the filename in XSL and pass it to the Java but in a static method it is useless as it need to access the arg0 which is a object and obviously non-static context.
Is this possible ? How do I get access to Dynamic Configuration from XSL through Java in 7.1 ?
I have successfully called a static method but that is no help.
Thanks in advance.

Suraj,
Unfortunately you link isnt operational but thankyou anyway, I have managed to call as Java class as per my original post, but a static method does not allow me to get a handle to the Dynamic Configuration Variables in the message.
It seems importing the 7.0 LIBS may be an option and Im not entirely sure I have that option.
It certainly isnt possible to use the JDK5 XML implementation to even call a static method on an Java OBJ from XSL (obviously the USE SAPXMLTOOLKIT option is there for a reason).
I think and again I could be wrong but direct access via XSLT..
LINK:http://help.sap.com/saphelp_nwpi71/helpdata/EN/e2/e13fcd80fe47768df001a558ed10b6/frameset.htm
Is what Im looking for, I shall report back success or failure but the doco seems to fit the bill. Im not sure why I wanted to instatiate a sperate Java class when it can all exist in the XSLT.

How to run a command prompt " command " through java code

hi all,
There is a command
"java -jar selenium-server.jar -interactive"
which i am running through command prompt after going to D:\MyFolder\Examples .
i want to execute this command using java code .please help

This has already been answered in your other two threads on this topic - http://forum.java.sun.com/thread.jspa?threadID=5221221&messageID=9898287#9898287 and http://forum.java.sun.com/thread.jspa?threadID=5221223&messageID=9898290#9898290.
For some reason you don't want to read the reference that tells you exactly how to do what you want and how to avoid the pitfalls - http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html .

Executing Unix command through Java

Hi,
Hi, I am trying to run some unix command through:
Runtime.getRuntime().exec("some unix command line");
I am running the code on Linux platform. However, I always got some errors. Here are the stack trace of them:
java.io.IOException: Cannot allocate memory
java.io.IOException: java.io.IOException: Cannot allocate memory
        at java.lang.UNIXProcess.<init>(UNIXProcess.java:148)
        at java.lang.ProcessImpl.start(ProcessImpl.java:65)
        at java.lang.ProcessBuilder.start(ProcessBuilder.java:451)
        at java.lang.Runtime.exec(Runtime.java:591)
        at java.lang.Runtime.exec(Runtime.java:429)
        at java.lang.Runtime.exec(Runtime.java:326)Anybody has any idea why is this happening? Thanks.
Aulia

Hi, thanks for your reply so far. I tried the following code:
     public boolean executeCommand() {
          boolean success = true;
          for (int i = 0; i < 5; i++) {
               Process p = null;
               try {
                    p = Runtime
                    .getRuntime()
                    .exec("ls");
                    InputStreamReader inR = new InputStreamReader(p
                              .getErrorStream());
                    BufferedReader buf = new BufferedReader(inR);
                    String line;
                    while ((line = buf.readLine()) != null) {
                         System.out.println(line);
                    p.destroy();
               } catch (Exception e) {
                    System.err.println(e.getMessage());
                    e.printStackTrace();
                    success = false;
               } finally {
                    p = null;
          return success;
     }However, it still throws the same exception. Yes, I put it in a tight loop, but not recursively.

Running OpenSSL command through Java Program

How do I execute openssl commands through a java program? Any packages or wrapper classes are there? Please help.
Thanks.

Hi!
What do you mean execute commands? Like: "openssl x509 -in cert.pem -out certout.pem" ??
In that case you can just try the following:
import java.lang.Runtime;
try {
Runtime.getRuntime().exec("openssl x509 -in cert.pem -out certout.pem");
}catch (Exception e) {
e.printStackTrace();
........

How to execute MS DOS command through Java program???

Dear Sir,
I want to run a MS-DOS command through my Java program. I have tried "Dir" command but no other command which takes command line args doesn't work at all. Please help.
import java.io.*;
class CommandPrompt
     public static void main(String[] args)
          try
               File file = new File("C:/Temp/Java");
               String[] cmd = {"command.com","/c","md folder"};
               String[] envp = {""};
               Process m;
               String s = "";
               m = Runtime.getRuntime().exec(cmd,null,file);
               BufferedReader buf = new BufferedReader(new InputStreamReader(m.getInputStream()));
               while ((s = buf.readLine())!=null)
                    System.out.println(s);
          catch (Exception ex)
               System.out.println("Exception is "+ex);
               ex.printStackTrace();

1. This forum is for Swing-related issues only. This question should be posted to the "Java Programming" forum.
2. Please enclose your sample code in code blocks; it's much easier to read that way. See here for how it's done: http://forum.java.sun.com/faq.jsp#messageformat
3. Please provide more information, like what error messages you got and what OS you're running. For instance, if you're running WinXP, Win2k or NT4, your command processor should be "cmd.exe", not "command.com". When I made that change, your program worked for me.

GETTING THE OUPUT OF UNIX COMMAND THROUGH JAVA

Hi Guyz...
Please help me in the below code...
My intention is to print the output of Unix command through a java program.
The Java program resides in the Unix Server only.
I have written the below java code , but its not returning any values....
String s1= "ls -lt $APPL_TOP/patch/115/odf/jtfgh.odf";
Runtime r = Runtime.getRuntime();
Process p= r.exec(s1);
StringBuffer ret=new StringBuffer();
InputStream in = p.getInputStream();
int c;
while ((c = in.read()) != -1)
{                  ret.append((char)c);
}     in.close();
out.println("OTUPUT : "+ ret.toString());
Can you please help me in this by debugging the existing code or giving me the exact code??
IT IS URGENT FOR MY PROJECT!!!!!!!!!!!!!!!!!!!!!!!!!!!
PLEASE HELP ME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Since you are expecting the shell to expand the environment variable you need to use
String[] s1= {"sh","-c","ls -lt $APPL_TOP/patch/115/odf/jtfgh.odf"};
Also, you should read, digest and implement the recommendations of
http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html .
P.S Your urgency is not my problem and SHOUTING IS CONSIDERED VERY RUDE!

Executing the top command through Java in linux

I am trying to execute the top command in Java as
Runtime.getRuntime().exec("top -n 1 >a.log");
But the command is not working in linux only through java.When i run the same command through the prompt it is working fine.Also all other commands are working fine.Is there any issue with top in linux?

flounder wrote:
Try reading [this article|http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html]. If it does not answer your problem then try seaching for other similar articles.
The cited article does provide an answer to the problem since it explains how the shell meta character '>' must be interpretted by a shell. The code as presented does not invoke a shell.

Getting result from a telnet command through Java

Hi,
I've been using a set of classes found here: http://javatelnet.org/
to do telnet through Java in a non-interactive mode.
However I've got a problem when retrieving the result of a command sent to the remote host: the classes read the stream until the prompt is encountered; my problem is I must execute commands on several remote hosts, and the prompt is not necessarily the same on all hosts.
Is there a simple means to establish a telnet connection through Java and retrieve the result of the commands?
Any help would be appreciated.

Thanks again, this is a very good article
I see it is still the same strategy to get the result of a command : wait 'til the prompt is sent. Maybe there is just no other way to get it .
But as I don't know the prompt on the different hosts I have to query, this won't do it.
The article gave me an idea though : I only need to count the files in a directory on the remote host; until now I was trying to send the 'ls | wc -l' command by Telnet.
Maybe I can simply do it by FTP (retrieve the list of files, and then count the lines with JAVA).

Host command through java stored procedure

Hi All,
Im trying to execute the winword command to open a MSWord document, print & exit the document, through dos prompt, from client pc to the default printer, through java stored procedure oracle pl/sql forms.
How can achieve this? Kindly help.
rgs
paul

If you have configured webutil without any problems then i presume you have configured jacob.jar file too for Client_ole2 to function properly you need to have jacob.jar and jacob.dll files.
There are so many topics in this forum for Client_Ole2. Just simply search. :)
Message was edited by:
Mudabbir

Accessing OS level commands through Java?

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