Compiling a C Source through javacode

Question

I am trying to compile a C program through a javacode. I did it as follows.

    Process process = Runtime.getRuntime().exec("C:/cygwin/bin/sh -c 'gcc HelloWorld.c -o HelloWorld.exe'");

    InputStream is = process.getInputStream();
    InputStreamReader isr = new InputStreamReader(is);
    BufferedReader br = new BufferedReader(isr);
    String line, log;
    log ="\n..Input..\n";
    while ((line = br.readLine()) != null) {
      log+=line;
      log+="\n";
    }

    InputStream is2 = process.getErrorStream();
    InputStreamReader isr2 = new InputStreamReader(is2);
    BufferedReader br2 = new BufferedReader(isr2);
    String line2;
    log+="\n..Error..\n";
    while ((line2 = br2.readLine()) != null) {
      log+=line2;
      log+="\n";
    }
    System.out.println(log);

HelloWorld.exe is not created and following error message was displayed. /usr/bin/sh: gcc: command not found

Stephen C · Accepted Answer · 2012-06-26 09:18:03Z

2

One problem is that exec(String) splits the string into arguments naively at the white-space characters. You need to do the splitting for it. write the exec as:

Process process = Runtime.getRuntime().exec(new String[]{
     "C:/cygwin/bin/sh",
      "-c",
      "gcc HelloWorld.c -o HelloWorld.exe"});

The exec(String) method does not understand shell syntax such as quoting and redirection.

It might also be necessary to use a full pathname for the gcc command, but I doubt it. The shell should inherit the environment variable settings from the JVM, and that probably includes a suitable PATH variable.

answered Jun 26, 2012 at 9:18

Stephen C

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2 Comments

Taani Over a year ago

tried this...this time the error message didn't appear. Nothing was displayed on console. Also HelloWorld.exe was also not created.

Stephen C Over a year ago

Try some experiments. 1) Try to run the command from the windows command prompt. 2) Replace "gcc HelloWorld.c -o HelloWorld.exe" with "cat HelloWorld.c" or "ls -l HelloWorld.c" or "ls -ld ."

sathish_at_madison · Accepted Answer · 2012-06-26 21:01:23Z

0

You can get the current run-time environment and invoke exec method. Here is an example:

String cmd="C:/cygwin/bin/sh -c '/usr/bin/gcc HelloWorld.c -o HelloWorld.exe'"; Process process = Runtime.getRuntime().exec(cmd);

edited Jun 26, 2012 at 21:01

sathish_at_madison

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answered Jun 26, 2012 at 9:10

Adam Sznajder

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1 Comment

Stephen C Over a year ago

That won't help. Read the javadoc for exec(String) to understand how it splits the string into arguments.

Arcadien · Accepted Answer · 2012-06-26 09:11:36Z

0

try

/usr/bin/gcc

rather than

gcc

say, use full path for binaries call in script.

answered Jun 26, 2012 at 9:11

Arcadien

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