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Lynx, Java, & Runtime.getRuntime().exec()

LYnx is a text based browser. It can convert .html files to its rough equivalent in text.

I am trying to use a simple java program to call lynx.bat or lynx.exe .

Lynx.bat is located in C:\Lynx\lynx.bat

I want to use the "-dump" parameter.

Then I must put the name of the file "mydoc.htm"

Then the name of the new file "mydoctxt.txt"

So in completion it would look like this "lynx.bat -dump mydoc.htm > mydoctxt.txt"

This works completely fine from the command line, but when I try to wrap it in a simple java program, it fails.

Here is what I have so far...

package javaapplication2;
import java.io.*;
class Main{

public static void main(String argv[]) {

try {
String ls_str;

//Process ls_proc = Runtime.getRuntime().exec("cmd.exe /E :1900 C:\\lynx\\lynx.exe -dump C:\\test.htm > C:\\test6.txt");
Process ls_proc = Runtime.getRuntime().exec("C:\\lynx\\lynx.bat -dump C:\\test.htm > C:\\test5.txt");

DataInputStream ls_in = new DataInputStream(
ls_proc.getInputStream());

try {
while ((ls_str = ls_in.readLine()) != null) {
System.out.println(ls_str);

}
} catch (IOException e) {
System.out.println("1st catch block");
System.exit(0);

}
} catch (IOException e1) {
System.err.println(e1);
System.out.println("2nd catch block");
System.exit(1);
}

System.exit(0);

}

}

When I run that a blank text file called test5.txt is created. It is 0kb in length. If I run it straight from the command line in windows XP though, test5.txt is created successfully. If I uncomment out Process ls_proc = Runtime.getRuntime().exec("cmd.exe /E :1900 C:\\lynx\\lynx.exe -dump C:\\test.htm > C:\\test6.txt"); and comment out the other line, the program lags and nothing happens.

I know I have to be missing something simple here, because I whipped up the equivalent prog in VB, in like 3 minutes.

gdrnec

I had this problem once and I think that I solved by using Runtime.exec(String[] cmdarray) method instead of all one string.

so String[] cmdarray = {"C:\\lynx\\lynx.bat","-dump","C:\\test.htm",">","C:\\test5.txt"};
Runtime.getRuntime().exec(cmdarray);

I think I remeber this solving it. Hope I'm right.

Geoff

zzynx

Sure it isn't a matter of (back) slashes.

Did you try these already?

Process ls_proc = Runtime.getRuntime().exec("cmd.exe /E :1900 C:/lynx/lynx.exe -dump C:/test.htm > C:/test6.txt");
or
Process ls_proc = Runtime.getRuntime().exec("C:/lynx/lynx.bat -dump C:/test.htm > C:/test5.txt");

ASKER CERTIFIED SOLUTION

Webstorm

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Mick Barry

Here an examples of handing the output from a Process that you should be able to easily adapt to your requirements.

http://www.objects.com.au/java/examples/util/ConsoleExec.do

bullyellis

ASKER

WebStorm,

Your code works kind of.

The problem I ran into was

RunProcess ls_proc = new RunProcess(
Runtime.getRuntime().exec("C:\\lynx\\lynx.bat -dump C:\\test.htm > C:\\test5.txt"),
System.in,false,
new FileOutputStream("C:\\test5.txt"),true, // stdout redirection
System.err,false);

The 2 instances of "test5.txt" can not be named the same thing.

I get an error that "The process cannot access the file because it is being used by another process." And again I get the empty text file.

However if I change the code to

RunProcess ls_proc = new RunProcess(
Runtime.getRuntime().exec("C:\\lynx\\lynx.bat -dump C:\\test.htm > C:\\testa.txt"),
System.in,false,
new FileOutputStream("C:\\testb.txt"),true, // stdout redirection
System.err,false);

Then I get both testa and testb. testa.txt works correctly and is what I want. testb.txt however is another empty text file.

Could you explain this ?

Webstorm

bullyellis, thanks for the points

When you specify a redirection with '>', cmd.exe will redirect output to this file. So, nothing will be written to the process's stdout stream, and you get an empty file.
If you specify a FileOutputStream you don't have to specify another redirection in the command line and it's only usable with cmd.exe :

RunProcess ls_proc = new RunProcess(
Runtime.getRuntime().exec("C:\\lynx\\lynx.bat -dump C:\\test.htm"),
System.in,false,
new FileOutputStream("C:\\testa.txt"),true, // stdout redirection
System.err,false);

Or

RunProcess ls_proc = new RunProcess(
Runtime.getRuntime().exec("C:\\lynx\\lynx.bat -dump C:\\test.htm > C:\\testa.txt"),
System.in,false,
System.out,false,
System.err,false);

Lynx, Java, &amp; Runtime.getRuntime().exec()

Lynx, Java, & Runtime.getRuntime().exec()