FerrousHombre
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How do I run two consecutive DOS commands through a ProcessBuilder object?
I'm trying to run DOS commands through a ProcessBuilder object in Java, and am able to get a single command to run, but not multiple. In the code below, I see a return from the processes' output stream for "cmd.exe", but not "dir" or "exit". Do I need to enter the commands differently?
(I'm on a Windows Vista machine.)
(I'm on a Windows Vista machine.)
String[] cmds = {"cmd.exe","dir","exit"};
ProcessBuilder processBuilder = new ProcessBuilder(cmds);
processBuilder.start();
You may also want to explore your options with that "&" symbol -
One ampersand means do this AND this
Two together (&&) mean do thing two only if thing one succeeded (nonzero exit code)
Two Pipes (||) mean do thing two only if thing one failed
you can also use parenthesis to logically group commands.
this page has a good overview of the ways you can use single line branching: http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/ntcmds_shelloverview.mspx?mfr=true
One ampersand means do this AND this
Two together (&&) mean do thing two only if thing one succeeded (nonzero exit code)
Two Pipes (||) mean do thing two only if thing one failed
you can also use parenthesis to logically group commands.
this page has a good overview of the ways you can use single line branching: http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/ntcmds_shelloverview.mspx?mfr=true
ASKER
I get an IOException:
java.io.IOException: Cannot run program "cmd.exe /c dir": CreateProcess error=2, The system cannot find the file specifiedSOLUTION
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ASKER
Hmm. It runs now, but I don't get any output. When I run it for just "cmd.exe", I'm able to print some output from the processes' input stream. But when I run for "cmd.exe","/c dir", I get no output. I need that so I can interrogate a process and confirm it's status.
If you run just cmd.exe, you get a visible box you can type commands in?
cmd.exe with /c option will execute a command or commandline, then exit. If you need the box, use /k instead of /c.
cmd.exe with /c option will execute a command or commandline, then exit. If you need the box, use /k instead of /c.
ASKER
No, I don't get a visible box. I take the Process created by ProcessBuilder.start(), use getInputStream() on the process, and read from that stream using a BufferedReader:
Process proc = processBuilder.start();
InputStream is = proc.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String readLine;
while(((readLine = br.readLine()) != null) && (readLine.trim().length() > 0)) {
System.out.println(readLine);
}SOLUTION
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ASKER
That, and ending each of the strings with a space, got it printing output again:
Now, technically, this statement only executes a single command, "/k dir ". I still need to run multiple commands, "cmd.exe" just doesn't need to be one of them.
ProcessBuilder processBuilder = new ProcessBuilder("cmd.exe ", "/k dir ");Now, technically, this statement only executes a single command, "/k dir ". I still need to run multiple commands, "cmd.exe" just doesn't need to be one of them.
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ASKER
Ah. I was able to get multiple commands to run (and return output) by invoking additional calls to ProcessBuilder.start(), so I got what I needed. Thanks!
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Though the exit is superfluous here.