In this question it shows that when you run a shell command from Java, it runs from the current directory. When I run the command javac Program.java from my program, it shows the error (from the standard error stream):
javac: file not found: Program.java
Usage: javac <options> <source files>
use -help for a list of possible options
However, when I run the same exact command from the actual Terminal, it works fine and saves the .class file in the default directory. This is the code:
Runtime rt = Runtime.getRuntime();
String command = "javac Program.java";
Process proc = rt.exec(command);
BufferedReader stdInput = new BufferedReader(new
InputStreamReader(proc.getInputStream()));
BufferedReader stdError = new BufferedReader(new
InputStreamReader(proc.getErrorStream()));
// read the output from the command
System.out.println("Here is the standard output of the command:\n");
String s = null;
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
}
// read any errors from the attempted command
System.out.println("Here is the standard error of the command (if any):\n");
while ((s = stdError.readLine()) != null) {
System.out.println(s);
}
proc.waitFor();
Any ideas why it works when I type it in the actual Terminal, but not when I run it from my program? I am running a Max OS X Mountain Lion (10.6)
Thanks
You can try to print the path in your programm ,use new File(".").getAbsolutePath() ,if you are in a ide ,the path may be in the root of the project rather than in the path of the current java file
Your program is probably being run from a different directory. Your IDE (such as Eclipse) is probably is running from one location, and knows the directory structure to access your program files.
The easiest, quickest solution is to just write the fully-qualified file path for Program.java.
The alternate is to find out what the current directory is. So, perhaps run pwd the same way you are running javac Program.java from within your program's code? Then you can see what directory your program is actually being run from. Once you know that, you can write the appropriate directory structure.
For example, if pwd reveals that you are actually 2 directories above where Program.java is, then you can put those directories in the command like this: javac ./dir1/dir2/Program.java.
To change the directory Eclipse runs from, see this question Set the execution directory in Eclipse?
The reason my code was not working was because I was running it in Eclipse IDE, and that messes up the directory the program is running from. To fix that program, I changed the command to javac -d . src/Program.java. If I export the program into a .jar file and run it in the desktop, my original command will do just fine.
Thanks to saka1029 for helping me!
Related
I'm trying to open a PDF file in Linux with the xdg-open command in java.
String[] command = {"xdg-open","\""+path+"\""}
Process p = Runtime.getRuntime().exec(command,null);
p.waitFor();
When I run the code in terminal nothing happens even tho if I type it in terminal:
xdg-open path
it opens the PDF.
Any ideas whats wrong?
You should not escape the path: if the program was called, it was with an invalid path ("path" and not path).
String[] command = {"xdg-open", path}
The Runtime.getRuntime().exec(command,null); will use ProcessBuilder internally which, in the case of Linux, should invoke the system command execve.
I am developing a Java application where one of its task is to execute a system command using Runtime exec. The command requires another JAR file to be able to work but whenever the part where the command will be executed, I am getting an "Error: Unable to access jarfile".
Firstly, my current working directory:
assets/jarFile.jar
myApp.jar
Here's what my code looks like:
try {
// To get the path of the directory where my current running JAR is
String jarPath = myApp.class.getProtectionDomain().getCodeSource().getLocation().getPath();
String path = URLDecoder.decode(jarPath.substring(0, jarPath.lastIndexOf("/")), "UTF-8");
// The system command to execute
String command = "java -Xmx1024m -jar "+path+"/assets/jarFile.jar and-so-on...";
Process p = Runtime.getRuntime().exec(command);
...
}
The jarFile.jar is not an executable JAR by the way.
Any idea?
Seems like your code to find the path of the jar file does not return the correct path.
I am trying to compile a c program from a java program on Linux platform. My snippet is.
ProcessBuilder processBuilder = new ProcessBuilder("/usr/bin/gcc",
"-c","/hipad/UserProject/example.c");
Process proc = processBuilder.start();
There is no error during compilation of java program but I am not able to get .o file. I tried to find out solutions but no one is working.
Any suggestion.....
The default working directory of a child process is what ever directory the Java process has as a working directory, which usually is where it was launched from. And by default gcc writes output files to current working directory. That's where you should find example.o.
There are two simple ways to solve this. You can give gcc -o option and full path and name of desired output file, or you can set working directory of child process, like this:
ProcessBuilder processBuilder =
new ProcessBuilder("/usr/bin/gcc", "-c","example.c"); // source in working dir
processBuilder.directory(new File ("/hipad/UserProject")); // or whatever
Process proc = processBuilder.start();
See ProcessBuilder javadoc for more info.
I want to execute a command from a Java-application using
Runtime.getRuntime.exec(command);
but the command need Admin-privileges. If I use
runas /user:Administrator "cmdName parameters"
nothing happens because I need to give user und pw as parameter to the command.
But I need to run a command to the cmd, so that a new cmd.exe starts as administrator and asks if I want to run cmd.exe as admin. After agree the command should be run in the admin-cmd. So like this:
String command = "popupNewCmdAsAdminAndRun "batWhichNeedsAdmin.bat" "
Runtime.getRuntime.exec(command);
Has anyone an Idea?
Thanks in advance!
you should do the following
Process process = new Process();
process.StartInfo.FileName = "cmd.exe";
process.StartInfo.Arguments = "command";
process.StartInfo.Verb = "runas";
process.Start();
process.WaitForExit(60000);
Start Command Prompt (CMD) from java as Administrator and Run command prompt as Administrator - or the silly way, try to pipe it:
pw | command
Research building projects and the executable jar file. Usually when you build a project, it gives you a commandline that can be used to execute the jar file in folder dist located in the projects folder. You can copy and paste the command line in cmd. But you could also use a bat file, or convert the executable jar file into an exe with the jar2exe converter. Not completely sure of the name because i am not posting on my computer.
I want to run some unix/shell commands in Java and process the output. I used getRuntime.exec(), but it is not giving correct output for some commands like ls directory_path/*.tar.gz . For that command my program is not giving any output but it is giving error saying No such file or directory. But the same command is giving correct output on command prompt.
Is there any other way to execute commands which include wildcards in Java?
Is there any other way to execute commands which include wildcards in Java?
Yes there is.
You have three potential problems in your code:
Assuming you want to see the output of the external command you need to take care of the output it produces, and print it yourself.
Follow the example I've provided over here:
How to make a java program to print both out.println() and err.println() statements?
The shell expansion of * doesn't work if you naively go through Runtime.exec.You have to go through /bin/bash explicitly.
If you try to list the content of directory_path/*.tar.gz you should know that (if you're not starting with a /) directory_path will be resolved relative to the current working directory. Try at first to give the absolute path to make sure it works, and then try to figure out why it can't find the relative path.
Here's a complete example that should work:
Process proc = new ProcessBuilder("/bin/bash", "-c",
"ls /.../directory_path/*.tar.gz").start();
Reader reader = new InputStreamReader(proc.getInputStream());
int ch;
while ((ch = reader.read()) != -1)
System.out.print((char) ch);
reader.close();
That is because you specified a relative path to the directory and your application is running in a working directory. The path you specified is relative to that working directory.
To find out what the absolute path is, you can check out the working directory.
System.out.println("Working directory: " + System.getProperty("user.dir"));
"ls directory_path/*.tar.gz" works relative to CURRENT directory.