Develop Reference

Running a shell command in a specific directory in java

I'm currently developing a little software in Java and I'm facing a problem I'm not able to solve. In a few words, I am on ArchLinux and I need to run "makepkg" in a specific directory. Of course I tried with
Runtime.getRuntime().exec("cd foo && makepkg");
But I discovered that I cannot cd in directories. Someone has an idea on how to do this? Thanks anyway

A process executor is not a shell. It's done for launching a process.
A thing that can help you is to launch the process from a specified directory.
You can create a ProcessBuilder instance and set the working directory.
It is my way of doing.
ProcessBuilder pb = new ProcessBuilder("makepkg");
pb.directory(new File("foo"));
final Process process = pb.start();
// then you read the flow with process.getInputStream() for example

Run some arguments in command line from java (using Eclipse)

Very basic command-line related question:
I have never tried to run anything in command line from java before and am struggling with the basics - other online information doesn't seem to work for my example, or I'm not understanding it.
In command line this is what it looks like:
C:\gnuplot\binary>gnuplot 15FebPlotFile.gp
All I have to do in command line is navigate to the correct file location (C:\gnuplot\binary) and then type gnuplot 15FebPlotFile.gp and it runs the thing I need (which simply generates a PDF and saves it to that file location)
I've seen people use Runtime and Process like on this site http://www.java-tips.org/java-se-tips/java.util/from-runtime.exec-to-processbuilder.html but I don't understand how I call the various command, like cd C:\gnuplot\binary and then from that location get it to run gnuplot 15FebPlotFile.gp.
If anyone could give me any advice on an approriate site to look at or some lines of code that might help me I'd be really greatful.
Thank you

You can work with ProcessBuilder, and then you can set the working directory of the process using ProcessBuilder#directory(File dir):
ProcessBuilder processBuilder = new ProcessBuilder("gnuplot", "15FebPlotFile.gp");
processBuilder.directory(new File("C:\\gnuplot\\binary"));
Process p = processBuilder.start();

I hope here you can find some code examples and solutions
Run command prompt from java?
changing the working-directory of command from java

Call Cygwin from Java app

I need to call Cygwin from Java code ( example : to call make command in Cygwin from Java app which run on linux and windows ).Does anybody have experience with this problem ?

I think you have to differentiate youre code for linux and windows
on linux simply execute the command
on windows lauch your command in cygwin with
C:\cygwin\bin\bash.exe --login -i -c <cmd>
note: you may use apache commons exec to lauch an external command from java

Use ProcessBuilder from Java:
http://download.oracle.com/javase/7/docs/api/java/lang/ProcessBuilder.html
You will need to make sure your path/environment is set up properly, but that depends on your machine and set up.
Also, note that many cygwin "capabilities" (e.g., less, awk, sed, etc) are simply binaries (executables) that you can call directly -- no need for the bash shell to facilitate access to those. Look at the actual files in wherever your bin folder is (usually c:/cygwin/bin) and try calling those directly from ProcessBuilder. If you need to actually leverage the shell (e.g., pipes, variables, globbing, etc) then that's a different story -- you would then integrate with the bash.exe file itself (check the man page for usage info).

How to use mkdir and rmdir commands in a java program

I want to use system commands like mkdir and rmdir while running a java program.
How can I do that?

Why do you want to use the command line? FYI, there are built-in platform-independent File classes.
http://www.exampledepot.com/egs/java.io/deletefile.html
http://www.roseindia.net/java/beginners/java-create-directory.shtml
Make directory:
new File("dir path").mkdir();
Remove directory:
new File("dir path").delete();
'new File' here is a bit of a misnomer, it isn't actually creating the directory or a file. It's creating a Java resource hook which you can use to query or operate upon an existing filesystem resource, or create a new one at your request. Otherwise, use Runtime.getRuntime().exec("command line here") for using command line operations (not advised!!).
Edit: sorted out the problem the question poster was having:
String envp[] = new String[1];
envp[0] = "PATH=" + System.getProperty("java.library.path");
Runtime.getRuntime().exec("command line here", envp);
Note the insertion of envp into the exec(..) method call, which is basically the PATH variable from the environment.

As the other mentioned, you shouldn't do this for simple file management. But to have it mentioned: The Java API has a class called Runtime, that allows system calls... for example:
Runtime.getRuntime().exec("some_command");

The best is not to, but rather find the pure Java API function that does it. It is cleaner, easier to understand and much less error prone. It is also the only way to do Java that is write once run everywhere. Once you are calling shell commands, you are tied to that shell.
In your case you are looking for the java.io.File class, and specifically the mkdir and delete methods.

For reference of people stumbling onto this question and wondering why Runtime.getRuntime().exec("mkdir foo") doesn't work even when incorporating the environment as per Chris Dennett's answer, the most probable reason is that you don't have a program called "mkdir" on your system. While most Unix-like systems have a program of this name, it isn't absolutely necessary for them to have one, and Windows doesn't have one, because in both cases the shell interprets this command itself, rather than passing it to an external program.
To make it work, try ...exec ("cmd /c mkdir foo") for NT-family Windows (or "command /c mkdir foo" for Windows 95 family), or exec ("sh -c \"mkdir foo\"") for Unix.
The fact that there isn't a platform-independent way to do this is yet another reason to prefer the Java APIs for performing the task.

Hi Agree to the fact of not been platform independent but just for testing an app I had to use it.
The solution in my case for the
Runtime.getRuntime().exec("my_command_name") ;
for not working was i had to give the full path to where the batch/sh/executable file was
ie:
Runtime.getRuntime().exec("/d/temp/bin/mybatfile");

Java ProcessBuilder showing console of started java application?

I have a JAVA application that launches (using ProcessBuilder) another JAVA application like this:
String val = "something";
ProcessBuilder processBuilder = new ProcessBuilder("java", "-classpath", dir, appName, val);
Process p = processBuilder.start();
Now, this works fine, appName is launched with the parameter val and it runs and works ... great ... the problem is no Console Window appears ... appName does a LOT of outputting to the console and we need to see it ... how can I start the process with a console?
I am trying stuff like ("CMD.exe", "java", "-classpath", dir, appName, val), etc... but I can't get it right ...
Also, I can't redirect the streams, my program can actually start 5-10 of these appName's, each should have their own console window showing their own information.
Any help would be much appreciated.
Thanks,

console windows are generally not the most reliable form of logging. they only store a set amount of information (buffer) and can behave differently across platforms.
i strongly suggest logging to a file using something like log4j and if you need to see it real time use a tail like program (i see you're using windows).
in addition to this, seeing as you want the windows visible at all times and launching a tail program for each log might be annoying, i'd write my own log window in java swing.
the basic idea is to not rely on the OS too much.

Tried Runtime.getRuntime().exec("cscript java -classpath ..."); ?
Anyway, consider using a logging framwork (log4j, commons-logging), because opening 5 consoles is not the most clever thing to do.

I call a few shell scripts via Process to open a command line window and launch whatever I need. As long as the scripts don't detach - you can usually stop any shell command from doing this -java will still hold the running process.
I did it in linux but the concept should be similar.
#!/bin/bash
# To open a process in a new window.
gnome-terminal -x ./your-real-shell-script-here.sh "$#"
the real script will have your java execution in it, such as:
#!/bin/bash
java -jar your-jar-file.jar "$#"
I think you can use javaw to run on windows, so you might only need the one shell script.

A Console object only exists when you execute java.... from a console. Otherwise, the call to obtain one returns null.
If you want to see a console, you need to open a command shell console (e.g. windows cmd.exe or Unix bash shell window) and type:
java -classpath="..." com.example.appName arg1
If you want to run in a different manner, sorry to say, logging to Console is not for you. Instead, log using one of:
log4j
slf4j
logback