Solved

Java RunTime exec method's Usage

Posted on 2009-07-14
15
585 Views
Last Modified: 2012-05-07
Hi; I try to use run following script by Runtime.getRuntime.exec. But I do not know how to write arguments.

String[] cmdArray = new String[]{"ps","awk","sort","uniq","awk","grep"};
String[] parameters = new String[]{"aux", "'{print $4 \"\\t\"$11}'"....",null,"-c","'{print $2\" \"$1\" \"$3}'","java"};
       
Process proc = Runtime.getRuntime.exect(cmdArray,parameters);

Am I right?

ps aux | awk '{print $4"\t"$11}' | sort | uniq -c | awk '{print $2" "$1" "$3}' | grep java
0
Comment
Question by:JianJunShen
  • 7
  • 4
  • 2
  • +1
15 Comments
 
LVL 20

Expert Comment

by:a_b
ID: 24850670
What is the error/issue that occurs when you run this? looks okay to me.
0
 
LVL 86

Assisted Solution

by:CEHJ
CEHJ earned 150 total points
ID: 24850675
With a command as complex as that, you would be much better advised to put it in a shell script and Runtime.exec that

But see

http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html
0
 
LVL 86

Assisted Solution

by:CEHJ
CEHJ earned 150 total points
ID: 24850700
That would be


String[] args = { "/bin/bash", "x.sh" };
Process p = Runtime.getRuntime().exec(args);

Open in new window

0
Free Tool: Postgres Monitoring System

A PHP and Perl based system to collect and display usage statistics from PostgreSQL databases.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

 

Author Comment

by:JianJunShen
ID: 24851464
where shall I put script file(x.sh)?

String[] args = { "/bin/bash", "x.sh" };
Process p = Runtime.getRuntime().exec(args);
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 24851509
Well a safe place would be in your home directory
0
 

Author Comment

by:JianJunShen
ID: 24857276
well, if one use eclipse, it is better to put in project root directory. Pararel to src folder.
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 24857313
:-)

btw, my comment at http:#24850675 is devoted to getting output
0
 
LVL 2

Accepted Solution

by:
nkiggs earned 350 total points
ID: 24867139
Hi,

To run complex commands you can simulate your multiple command line arguments with a bufferedwriter writing to the shell you create. So you will have all the commands like:

/bin/sh
cd ..
pwd
exit

to create a shell(or you can use /bin/csh) go one directory backwards(cd ..) and then finally print the working directory (pwd) and finally exit (exit) after reading with the bufferedreader output from pwd command. Code example below to do this. Alter to suite the order you would type your commands in your shell script.
  	public int runProcess(){
      	// code to commence processing		
		String line;
		File wd = new File("/bin");	//location of sh executable 
		Process proc = null; 
		
		try { 
			proc = Runtime.getRuntime().exec("/bin/sh", null, wd); 
		} 
		catch (IOException e) { 
			e.printStackTrace(); 
		} 
		
		if (proc != null) { 
			BufferedReader in = new BufferedReader(new InputStreamReader(proc.getInputStream())); 
			PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(proc.getOutputStream())), true); 
			out.println("cd ..");	
			out.println("pwd");				
			out.println("exit"); 
			try { 	
				int x = 0;
				while ((line = in.readLine()) != null) { 
					if (x > -1){
						System.out.println(line + "\n");
					}
					x++;				
				} 
				proc.waitFor(); 
				in.close(); 
				out.close(); 
				proc.destroy(); 
			} 
			catch (Exception e) { 
				e.printStackTrace(); 
			} 
		}      		
   	}

Open in new window

0
 
LVL 2

Expert Comment

by:nkiggs
ID: 24867188
Hi,

You can simulate all the commands you will normally enter into your shell script window by using both BufferedReader and BufferedWriter simultaneously. Therefore, your application would operate as if you are entering commands manually (BufferedWriter) and get all the output as you enter commands (BufferedReader).

This output can be manipulated with a variable x that tracks the number of lines outputed and you can use this output by manipulating the string "line".

See my comment on the question.

Regards,

nkiggs
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 24874504
nkiggs probably didn't intend to object i'd guess
0
 

Author Comment

by:JianJunShen
ID: 24874618
I think ID:24867139 is the best solution.       ID:24850700 is assistant answer. It is also a good one.
0
 

Author Closing Comment

by:JianJunShen
ID: 31603292
Experts answer are excellent.
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 24874652
The late addition is only appropriate when you for some reason want to run an interactive shell from within Java, which was certainly not mentioned as a requirement...
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 24874657
*Is* it a requirement JianJunShen?
0

Featured Post

Free Tool: Postgres Monitoring System

A PHP and Perl based system to collect and display usage statistics from PostgreSQL databases.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
session migration servlets 2 42
servlet  URL Rewriting 1 42
MySQL  on Tomcat 8 68
configure dependency in POM for new database 3 34
Are you developing a Java application and want to create Excel Spreadsheets? You have come to the right place, this article will describe how you can create Excel Spreadsheets from a Java Application. For the purposes of this article, I will be u…
Introduction Java can be integrated with native programs using an interface called JNI(Java Native Interface). Native programs are programs which can directly run on the processor. JNI is simply a naming and calling convention so that the JVM (Java…
Viewers learn about the third conditional statement “else if” and use it in an example program. Then additional information about conditional statements is provided, covering the topic thoroughly. Viewers learn about the third conditional statement …
The viewer will learn how to implement Singleton Design Pattern in Java.

808 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question