How to execute cmd commands via Java

Question

I am trying to execute command line arguments via Java  For example      Execute command String command    cmd  c start cmd exe   Process child   Runtime getRuntime   exec command       Get output stream to write from it OutputStream out   child getOutputStream     out write  cd C    r n  getBytes     out flush    out write  dir  r n  getBytes     out close      The above opens the command line but does not execute cd or dir  Any ideas  I am running Windows XP  JRE6    I have revised my question to be more specific  The following answers were helpful but do not answer my question

User · Answer

Try this link  You do not use  cd  to change the directory from which to run your commands  You need the full path of the executable you want to run   Also  listing the contents of a directory is easier to do with the File Directory classes

User · Answer

Every execution of exec spawns a new process with its own environment   So your second invocation is not connected to the first in any way   It will just change its own working directory and then exit  i e  it s effectively a no-op    If you want to compose requests  you ll need to do this within a single call to exec   Bash allows multiple commands to be specified on a single line if they re separated by semicolons  Windows CMD may allow the same  and if not there s always batch scripts   As Piotr says  if this example is actually what you re trying to achieve  you can perform the same thing much more efficiently  effectively and platform-safely with the following   String   filenames   new java io File  C     list

User · Answer

The code you posted starts three different processes each with it s own command  To open a command prompt and then run a command try the following  never tried it myself    try          Execute command     String command    cmd  c start cmd exe       Process child   Runtime getRuntime   exec command           Get output stream to write from it     OutputStream out   child getOutputStream         out write  cd C    r n  getBytes         out flush        out write  dir  r n  getBytes         out close      catch  IOException e

User · Answer

try       String command    quot Command here quot       Runtime getRuntime   exec  quot cmd  c start cmd exe  K  quot    command     catch  IOException e        e printStackTrace

User · Answer

This because every runtime exec     returns a Process class that should be used after the execution instead that invoking other commands by the Runtime class  If you look at Process doc you will see that you can use   getInputStream   getOutputStream     on which you should work by sending the successive commands and retrieving the output

User · Answer

Writing to the out stream from the process is the wrong direction    out  in that case means from the process to you   Try getting writing to the input stream for the process and reading from the output stream to see the results

User · Answer

As i also faced the same problem and because some people here commented that the solution wasn t working for them  here s the link to the post where a working solution has been found   https   stackoverflow com a 24406721 3751590  Also see the  Update  in the best answer for using Cygwin terminal

User · Answer

If you want to run several commands in the cmd shell then you can construct a single command like this     rt exec  cmd  c start cmd exe  K   cd c    amp  amp  dir        This page explains more

User · Answer

I found this in forums oracle com  Allows the reuse of a process to execute multiple commands in Windows  http   kr forums oracle com forums thread jspa messageID 9250051  You need something like     String   command                  cmd              Process p   Runtime getRuntime   exec command       new Thread new SyncPipe p getErrorStream    System err   start        new Thread new SyncPipe p getInputStream    System out   start        PrintWriter stdin   new PrintWriter p getOutputStream         stdin println  dir c     A  Q           write any other commands you want here     stdin close        int returnCode   p waitFor        System out println  Return code       returnCode     SyncPipe Class   class SyncPipe implements Runnable   public SyncPipe InputStream istrm  OutputStream ostrm          istrm    istrm        ostrm    ostrm        public void run           try                   final byte   buffer   new byte 1024             for  int length   0   length   istrm  read buffer      -1                              ostrm  write buffer  0  length                             catch  Exception e                    e printStackTrace                  private final OutputStream ostrm     private final InputStream istrm

User · Answer

Here is a simpler example that does not require multiple threads  import java io IOException  import java io InputStream  import java io OutputStream   public class SimplePty       public SimplePty Process process  throws IOException               while  process isAlive                          sync process getErrorStream    System err               sync process getInputStream    System out               sync System in  process getOutputStream                              private void sync InputStream in  OutputStream out  throws IOException               while  in available    gt  0                        out write in read                 out flush                             public static void main  String   args   throws IOException               String os   System getProperty  quot os name quot   toLowerCase            String shell   os contains  quot win quot      quot cmd quot     quot bash quot           Process process   new ProcessBuilder shell  start            new SimplePty process

User · Answer

Each of your exec calls creates a process  You second and third calls do not run in the same shell process you create in the first one  Try putting all commands in a bat script and running it in one call  rt exec  cmd myfile bat    or similar

[java] How to execute cmd commands via Java

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