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).
Related
I need to execute a jar file on HP-UX that I am not supposed to modify.
I unpacked it using jd-gui and found out that I am failing cause in java there is a condition to check the os, leading to different directions for win, macos, freebds, openbds, gnu and so on.
I am quite sure everything would work if I would be able to make my unix command line reply freebds or openbds to the java call
System.getProperty("os.name")
once executed from a jar file like:
java -jar myjar.jar
is there a way to achieve this? some kind of compatibility mode or a way to preset that parameter.
You can use the -D switch to specify system properties. In my experiment this (unexpectedly) even worked with pre-defined ones like os.name. Therefore this should work:
java -Dos.name=linux -jar myjar.jar
I have a Main.java file and I want to run the program passing it test.txt
I know in command line I can write javac Main.java
After compiling I can write java Main test.txt and this will accomplish running the file and passing test.txt
If I wanted instead to be able to just write main test.txt and have that trigger my Main.class file to run is that possible and if so how?
(Edit: Based on your comment, let me expand to add a couple more situations)
If your goal is to have someone else run your program who does not have Java installed, and you do not wish to have them install a Java runtime environment before running your app, what you need is a program that converts the .class or .jar files into a native executable for the platform you are using. How to do this has been covered in other questions, eg: Compiling a java program into an executable . Essentially, you use a program like JCG (GNU Compiler for Java) or Excelsior JET (a commercial product) to expand the byte code into full native code with a mini-JRE built in.
If your goal is to save typing, there are a number of strategies. Others have suggested alias commands, which work well on linux.
A slightly more portable option that you could ship with your program would be a shell script. Granted, shell scripts only run on linux or other OS's with shell script interpreters installed.
Here is an example shell script. You paste this into a text editor and save it as main with no extensio. The $1 passes the parameter argument fyi.
#!/bin/sh
java Main $1
presuming you name your shell script just "main" with no extension, you could call main test.txt to execute your program now.
If you are on Windows, you might want to create a windows shortcut, and point the shortcut to "java Main test.text", using the full paths if necessary (if the paths are not already set). Of course, this does not make the parameter easy to change every time you run it, you would have to edit the shortcut.
add an alias
e.g. under a mac edit your .bash_profile with the following line
alias main='java main'
don't forget to open a new console to see your alias working
Depends on your operating system. On Linux with the bash shell, for instance, you can set up an alias to expand your main into java -cp myjar.jar main.
Linux can also be configured to 'understand' Java class flies as a binary format directly see here (linux kernel documentation).
If you're on windows, you'll have to wait for answer from someone with more knowledge about that than I.
Good luck!
I'm trying to write Java code that executes some terminal commands. The code should execute this command sudo mount -o loop system.img system. But there are several problems. First, to execute this command I have to be root. I know that I can be by sudo su, but how can I stay as root when I close the terminal window? If I use the command sudo mount -o loop system.img system how can I provide the password in the Java code?
The second issue is: can I execute the command as below?
File f2 = new File("/home/user1/Desktop/aDirectory");
String[] commands = new String[]{"sudo mount", "-o", "loop", "/home/user1/Desktop/aDirectory/system.img"};
Runtime.getRuntime().exec(commands, null, f2);
I think I can't. So how can I do it? Any ideas?
Notes: system.img is a compiled Android os file. and the system is an empty directory. The thing I'm trying to do is mount the system.img file into the system directory.
Programs like sudo read the password directly from the terminal device, not from stdin, so this is unfortunately not a trivial thing to do. I'm not sure if this is realistic for Android or not, but on a general UNIX system the easiest solution is to use expect, which is a library for simulating a terminal and thereby automating these kinds of interactions. It's often used as a standalone program embedded in Tcl, and I've thrown together systems in which Java launched expect to talk to tools like sudo, and it works fine.
expect includes a sort of declarative scripting language that tells it how to run another program and how to react to that program's output.
What you would do is use Runtime.exec() to execute the expect program, supplying a script that just runs "sudo mount", watches for the password prompt, and provides the password. The script would probably just look something like (G4rb4geB4rg3 is the password):
spawn sudo mount -o loop /home/user1/Desktop/aDirectory/system.img
expect "password:"
send "G4rb4geB4rg3\r"
expect eof
The problem was solved, by using shell script.
I wrote a script includes just this line :
echo myPassword | sudo -S mount -o loop system.img system
then I run it in my java code, such :
Runtime.getRuntime().exec("sh 1.sh");
I'm pretty sure 'sudo' and 'mount' would be separate, since it's not a single executable you're invoking. Also, if you start sudo with the -S command line switch it can take the password directly from stdin, so you just need to start the process and pass in whatever the password's configured as to the input stream.
I'm using a bat file to run my jar. The code in my bat file is this :
#echo off
java -cp analyser.jar be.model.Start
pause
This works fine for windows.
But it doesn't do anything at linux. I also need to be sure it will run on Mac
Bat files are specific to Windows. You would need to execute the command in Linux and Mac in a manner that is specific to those platforms. The actual java call should work the same, I believe. The one change to the java line would be if you had multiple items in the classpath. In that case, you would need to use a colon as a separator instead of a semicolon (which is what Windows uses). (Thanks to khachik for that tip)
For Linux, you would use Shell programming using a BASH script. Here is a link that will describe what you need to do:
http://www.tldp.org/HOWTO/Bash-Prog-Intro-HOWTO.html
For Mac, you would probably use an AppleScript. Here is an article on how to get started with AppleScripts:
http://www.macosxautomation.com/applescript/firsttutorial/index.html
For Linux, why not use a .sh (shell) file?
As Biggs~ alreay said, the actual Java call should remain the same.
Update:
You will also have to make it executable by changing it's user permissions. To do this, use: chmod +x thescript.sh
I'm writing a Java Swing Application running on Red Hat Enterprise Linux 5 server that I would like to launch jEdit to view log files.
Here is some example code.
public static void main(String[] args) throws IOException, InterruptedException {
String cmd = "sh -c \"java -jar /tmp/jEdit/jedit.jar /tmp/test.txt\"";
System.out.println(cmd);
Runtime.getRuntime().exec(cmd);
}
The output is:
sh -c "java -jar /tmp/jEdit/jedit.jar /tmp/test.txt"
If I copy and paste the cmd output in a terminal window, it runs fine.
I have tried a bunch of cmd values, but I can never get the jEdit window to be visible.
With changes, this process works fine on Windows.
Is what I'm doing possible on Linux?
Thanks in advance!
As jEdit is implemented in Java, perhaps it would be easier to check the source for what the main method (in the class declared in the manifest file included in the jedit.jar) does and do the same thing without using Runtime.getRuntime().exec() at all.
If you do want to stick with it, you could try passing the individual commands as an array to exec(), this often solved such problems for me.
Linux uses the concept of display ports for its X-Windows system. This allows it to maintain a different desktop environment for each user. It also allows a user on remote machine to run a desktop app from the first machine but see the UI on the remote.
Windows, having only one available desktop environment at a time, does not.
First thing you definitely have to do is add the environment variable "DISPLAY=localhost:0" to the environment from which you are launching this. However, you may also need to run 'xhost +localhost' or this may not be allowed.
Double-check, too, that you didn't successfully launch a bunch of jEdit processes that are now zombies (using top) and kill them if necessary (using kill).
Runtime.exec() needs some special attention. The exec method that accepts a String uses the space character as a delimiter to break up the string into commands. You need to use the exec method that accepts a String[]. Read more here, specifically near the bottom.
I´ve done this once and I got the same problem
What I've done is to write the command line into a text file and then execute the text file as a shell script file.
It worked fine for me.
Jedit has a launcher script, /usr/bin/jedit I guess. Simply typing jedit in command prompt runs it, at least in current version, 4.5. Try that script instead of explicit java command.