java runtime, and bash

This is a discussion on java runtime, and bash within the Linux Programming forums, part of the Platform Specific Boards category; I think I have read at least 20 or so of the posts, and have not seen this question answered ...

  1. #1
    essence of digital xddxogm3's Avatar
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    java runtime, and bash

    I think I have read at least 20 or so of the posts, and have not seen this question answered yet.
    I want to run 3 consecutive commands on the system.
    Code:
    Runtime rt = Runtime.getRuntime();
    process pr = rt.exec("cdparanoia -w 1 track1; cdparanoia -w 2 track2");
    p.waitFor();
    Is this valid?
    I want to have linux execute mutiple bash commands one after another.
    or should I loop it like so.
    Code:
    Runtime rt = Runtime.getRuntime();
    String CommandString;
    process pr;
    for (int x=0;x<NumberOfTracks;x++)
    {
      CommandString="cdparanoia -w  "+x+" track"+x;
      pr = rt.exec(CommandString);
      p.waitFor();
    }
    by the way I have read the page
    http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html
    "Hence to fight and conquer in all your battles is not supreme excellence;
    supreme excellence consists in breaking the enemy's resistance without fighting."
    Art of War Sun Tzu

  2. #2
    Registered User linuxdude's Avatar
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    I want to have linux execute mutiple bash commands one after another.
    Like this
    Code:
    mplayer * -shuffle && echo "done" && exit

  3. #3
    essence of digital xddxogm3's Avatar
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    linuxdude,
    thanks for the response.
    I have a follow up question for you.
    Code:
    mplayer * -shuffle && echo "done" && exit
    Will the && wait to execute the next command after the prior one has completed.
    also what is the difference between what you wrote and the following
    Code:
    mplayer * -shuffle; echo "done"; exit
    "Hence to fight and conquer in all your battles is not supreme excellence;
    supreme excellence consists in breaking the enemy's resistance without fighting."
    Art of War Sun Tzu

  4. #4
    End Of Line Hammer's Avatar
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    The && is a conditional test. The order of statements are run left to right, as soon as one is deemed to be false, execution halts, no further statements are run. When using the semi-colon, that is a command separator, all statements are executed in order.
    Code:
     $ echo "1" && true && echo "2"
     1
     2
     
     $ echo "1" && false && echo "2"
     1
     
     $ echo "1"; false; echo "2"
     1
     2
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  5. #5
    essence of digital xddxogm3's Avatar
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    thanks hammer.
    another question involving bash commands and script files.
    I was advised in this thread.
    http://forum.java.sun.com/thread.jsp...rt=0&trange=15
    to use io processes.
    how would I have a bash script send input/output data to the java interface?
    "Hence to fight and conquer in all your battles is not supreme excellence;
    supreme excellence consists in breaking the enemy's resistance without fighting."
    Art of War Sun Tzu

  6. #6
    End Of Line Hammer's Avatar
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    >>... to the java interface?
    Don't know, this primarily a C/C++ programming forum.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  7. #7
    essence of digital xddxogm3's Avatar
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    then let me rephrase the question for a more specific need.
    Since I want to be able to do this in c, c++, and java.
    how would I have a bash script and c/c++ program communicate to each other?
    would I write everything to a .txt file and read it in on either side or is there another way?
    "Hence to fight and conquer in all your battles is not supreme excellence;
    supreme excellence consists in breaking the enemy's resistance without fighting."
    Art of War Sun Tzu

  8. #8
    End Of Line Hammer's Avatar
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    It depends on what you want to "communicate". Are we talking about long running programs, where both the script and program stay running indefinately, chatting to each other?

    If C/C++ you can use popen(), if you're compiler supports it. You could also use pipes.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  9. #9
    Obsessed with C chrismiceli's Avatar
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    does java support posix signals, mabey you could catch some of those?
    Help populate a c/c++ help irc channel
    server: irc://irc.efnet.net
    channel: #c

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