How to run Unix shell script from Java code

Question

It is quite simple to run a Unix command from Java    Runtime getRuntime   exec myCommand     But is it possible to run a Unix shell script from Java code  If yes  would it be a good practice to run a shell script from within Java code

User · Answer

You can use Apache Commons exec library also.

Example :

package testShellScript;

import java.io.IOException;
import org.apache.commons.exec.CommandLine;
import org.apache.commons.exec.DefaultExecutor;
import org.apache.commons.exec.ExecuteException;

public class TestScript {
    int iExitValue;
    String sCommandString;

    public void runScript(String command){
        sCommandString = command;
        CommandLine oCmdLine = CommandLine.parse(sCommandString);
        DefaultExecutor oDefaultExecutor = new DefaultExecutor();
        oDefaultExecutor.setExitValue(0);
        try {
            iExitValue = oDefaultExecutor.execute(oCmdLine);
        } catch (ExecuteException e) {
            System.err.println("Execution failed.");
            e.printStackTrace();
        } catch (IOException e) {
            System.err.println("permission denied.");
            e.printStackTrace();
        }
    }

    public static void main(String args[]){
        TestScript testScript = new TestScript();
        testScript.runScript("sh /root/Desktop/testScript.sh");
    }
}

For further reference, An example is given on Apache Doc also.

User · Answer

I think you have answered your own question with  Runtime getRuntime   exec myShellScript     As to whether it is good practice    what are you trying to do with a shell script that you cannot do with Java

User · Answer

I would say that it is not in the spirit of Java to run a shell script from Java  Java is meant to be cross platform  and running a shell script would limit its use to just UNIX   With that said  it s definitely possible to run a shell script from within Java  You d use exactly the same syntax you listed  I haven t tried it myself  but try executing the shell script directly  and if that doesn t work  execute the shell itself  passing the script in as a command line parameter

User · Answer

It is possible  just exec it as any other program   Just make sure your script has the proper     she-bang  line as the first line of the script  and make sure there are execute permissions on the file   For example  if it is a bash script put    bin bash at the top of the script  also chmod  x     Also as for if it s good practice  no it s not  especially for Java  but if it saves you a lot of time porting a large script over  and you re not getting paid extra to do it    save your time  exec the script  and put the porting to Java on your long-term todo list

User · Answer

Here is an example how to run an Unix bash or Windows bat cmd script from Java  Arguments can be passed on the script and output received from the script  The method accepts arbitrary number of arguments   public static void runScript String path  String    args        try           String   cmd   new String args length   1           cmd 0    path          int count   0          for  String s   args                cmd   count    args count - 1                     Process process   Runtime getRuntime   exec cmd           BufferedReader bufferedReader   new BufferedReader new InputStreamReader process getInputStream              try               process waitFor              catch  Exception ex                System out println ex getMessage                       while  bufferedReader ready                  System out println  Received from script      bufferedReader readLine                     catch  Exception ex            System out println ex getMessage             System exit 1             When running on Unix Linux  the path must be Unix-like  with     as separator   when running on Windows - use      Hier is an example of a bash script  test sh  that receives arbitrary number of arguments and doubles every argument      bin bash counter 0 while      -gt 0   do   echo argument    counter   1     1   echo doubling argument    counter        1  1     shift done   When calling   runScript  path to script test sh    1    2     on Unix Linux  the output is   Received from script  argument 1  1 Received from script  doubling argument 1  2 Received from script  argument 2  2 Received from script  doubling argument 2  4   Hier is a simple cmd Windows script test cmd that counts number of input arguments    echo off set a 0 for   x in      do Set  A a  1  echo  a  arguments received   When calling the script on Windows    runScript  path to script  test cmd    1    2    3     The output is  Received from script  3 arguments received

User · Answer

You should really look at Process Builder   It is really built for this kind of thing   ProcessBuilder pb   new ProcessBuilder  myshellScript sh    myArg1    myArg2     Map lt String  String gt  env   pb environment     env put  VAR1    myValue     env remove  OTHERVAR     env put  VAR2   env get  VAR1      suffix     pb directory new File  myDir      Process p   pb start

User · Answer

To avoid having to hardcode an absolute path  you can use the following method that will find and execute your script if it is in your root directory   public static void runScript   throws IOException  InterruptedException       ProcessBuilder processBuilder   new ProcessBuilder    nameOfScript sh          Sets the source and destination for subprocess standard I O to be the same as those of the current Java process      processBuilder inheritIO        Process process   processBuilder start         int exitValue   process waitFor        if  exitValue    0               check for errors         new BufferedInputStream process getErrorStream             throw new RuntimeException  execution of script failed

User · Answer

Yes  it is possible and you have answered it  About good practises  I think it is better to launch commands from files and not directly from your code  So you have to make Java execute the list of commands  or one command  in an existing  bat   sh    ksh     files   Here is an example of executing a list of commands in a file MyFile sh       String   cmd      sh    MyFile sh     pathOfTheFile        Runtime getRuntime   exec cmd

User · Answer

String scriptName   PATH   myScript sh     String commands     new String   scriptName  myArg1    myArg2       Runtime rt   Runtime getRuntime      Process process   null    try        process   rt exec commands         process waitFor       catch Exception e         e printStackTrace

User · Answer

for linux use  public static void runShell String directory  String command  String   args  Map lt String  String gt  environment        try               if directory trim   equals                  directory                 String   cmd   new String args length   1           cmd 0    command           int count   1           for String s   args                        cmd count    s              count                       ProcessBuilder pb   new ProcessBuilder cmd            Map lt String  String gt  env   pb environment             for String s   environment keySet                env put s  environment get s             pb directory new File directory             Process process   pb start             BufferedReader inputReader   new BufferedReader new InputStreamReader process getInputStream              BufferedWriter outputReader   new BufferedWriter new OutputStreamWriter process getOutputStream              BufferedReader errReader   new BufferedReader new InputStreamReader process getErrorStream               int exitValue   process waitFor             if exitValue    0     has errors                       while errReader ready                                  LogClass log  ErrShell      errReader readLine    LogClass LogMode LogAll                                   else                       while inputReader ready                                  LogClass log  Shell Result       inputReader readLine    LogClass LogMode LogAll                                     catch Exception e                LogClass log  Err  RunShell      e toString    LogClass LogMode LogAll            public static void runShell String path  String command  String   args        try               String   cmd   new String args length   1            if  path trim   isEmpty                cmd 0    path         command          else             cmd 0    command           int count   1           for String s   args                        cmd count    s              count                       Process process   Runtime getRuntime   exec cmd            BufferedReader inputReader   new BufferedReader new InputStreamReader process getInputStream              BufferedWriter outputReader   new BufferedWriter new OutputStreamWriter process getOutputStream              BufferedReader errReader   new BufferedReader new InputStreamReader process getErrorStream               int exitValue   process waitFor             if exitValue    0     has errors                       while errReader ready                                  LogClass log  ErrShell      errReader readLine    LogClass LogMode LogAll                                   else                       while inputReader ready                                  LogClass log  Shell Result      inputReader readLine    LogClass LogMode LogAll                                     catch Exception e                LogClass log  Err  RunShell      e toString    LogClass LogMode LogAll             and for usage   ShellAssistance runShell      pg dump   new String    -U    aliAdmin    -f     home Backup sql    StoresAssistanceDB       OR  ShellAssistance runShell      pg dump   new String    -U    aliAdmin    -f     home Backup sql    StoresAssistanceDB    new Hashmap lt  gt

User · Answer

I think with  System getProperty  os name       Checking the operating system on can manage the shell bash scrips  if such are supported  if there is need to make the code portable

User · Answer

The ZT Process Executor library is an alternative to Apache Commons Exec  It has functionality to run commands  capturing their output  setting timeouts  etc   I have not used it yet  but it looks reasonably well-documented   An example from the documentation  Executing a command  pumping the stderr to a logger  returning the output as UTF8 string    String output   new ProcessExecutor   command  java    -version        redirectError Slf4jStream of getClass    asInfo         readOutput true  execute        outputUTF8      Its documentation lists the following advantages over Commons Exec    Improved handling of streams   Reading writing to streams Redirecting stderr to stdout  Improved handling of timeouts Improved checking of exit codes Improved API   One liners for quite complex use cases One liners to get process output into a String Access to the Process object available Support for async processes   Future     Improved logging with SLF4J API Support for multiple processes

User · Answer

As for me all things must be simple   For running script just need to execute  new ProcessBuilder  pathToYourShellScript   start

User · Answer

Here is my example  Hope it make sense   public static void excuteCommand String filePath  throws IOException      File file   new File filePath       if  file isFile             throw new IllegalArgumentException  The file     filePath     does not exist              if isLinux             Runtime getRuntime   exec new String      bin sh    -c   filePath   null        else if isWindows             Runtime getRuntime   exec  cmd  c start     filePath           public static boolean isLinux        String os   System getProperty  os name          return os toLowerCase   indexOf  linux    gt   0     public static boolean isWindows        String os   System getProperty  os name        return os toLowerCase   indexOf  windows    gt   0

User · Answer

Just the same thing that Solaris 5 10 it works like this   batchstart sh there is a trick I don  t know if your OS accept it use     batchstart sh instead  This double slash may help

User · Answer

This is a late answer  However  I thought of putting the struggle I had to bear to get a shell script to be executed from a Spring-Boot application for future developers     I was working in Spring-Boot and I was not able to find the file to be executed from my Java application and it was throwing FileNotFoundFoundException  I had to keep the file in the resources directory and had to set the file to be scanned in pom xml while the application was being started like the following     lt resources gt       lt resource gt           lt directory gt src main resources lt  directory gt           lt filtering gt true lt  filtering gt           lt includes gt               lt include gt      xml lt  include gt               lt include gt      properties lt  include gt               lt include gt      sh lt  include gt           lt  includes gt       lt  resource gt   lt  resources gt   After that I was having trouble executing the file and it was returning error code   13  Permission Denied  Then I had to make the file executable by running this command - chmod u x myShellScript sh    Finally  I could execute the file using the following code snippet    public void runScript         ProcessBuilder pb   new ProcessBuilder  src main resources myFile sh        try           Process p          p   pb start          catch  IOException e            e printStackTrace              Hope that solves someone s problem

User · Answer

Yes it is possible to do so  This worked out for me   import java io BufferedReader  import java io IOException  import java io InputStreamReader   import org omg CORBA portable InputStream   public static void readBashScript             try               Process proc   Runtime getRuntime   exec   home destino workspace JavaProject listing sh        Whatever you want to execute             BufferedReader read   new BufferedReader new InputStreamReader                      proc getInputStream                  try                   proc waitFor                  catch  InterruptedException e                    System out println e getMessage                               while  read ready                      System out println read readLine                             catch  IOException e                System out println e getMessage

[java] How to run Unix shell script from Java code?

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