On Tue, 17 Aug 1999, Amlan Saha wrote:
> Hi there
>
> I am trying to write a Java wrapper for some C libraries. I have
> gotten most of it working except that I am not able to launch
> programs from the C libaries. I have a standard C-shared object
> library where I define a function using
>
> JNIEXPORT int JNICALL Java_API_Mypackage_myfunction
> (JNIEnv *env, jobject theObj)
> {
> fprintf(stdout,"Entered myfunction ...");
> execv("/sbin/ifconfig",NULL);
> return(errno);
> }
>
> which I then call from my java program by -
> API.Mypackage n = new API.Mypackage();
> int ret = n.myfunction();
> System.out.println(ret);
>
> However, this method does not result in printing out the ethernet
> interface information as it should if the program had executed the
> "/sbin/ifconfig" program. It just prints till the "Entered
> myfunction..." part and then exits. ERRNO reports "number 2" which
> is "no such file or directory" while I KNOW that it is there.
>
> This is what I get -
>
> [amlan@catbert jwrapper]$ java TestTheWrapper
> Entered myfunction...
> 2
> [amlan@catbert jwrapper]$
>
> What am I doing wrong ??
As Linux Programmer's Manual says the syntax of execv() is:
'int execv( const char *path, char *const argv[]);'
You should give "/sbin" as the first argument of execv() and "ifconfig" as
argv[0] or use execvp() instead of execv() and probably give "ifconfig" as
argv[0]. As you should know, in C argv[0] is the name of the executed
program and the rest of argv[] are the arguments for the program. Try 'man
execv' for further details.
Harri
Harri Sunila
Research assistant
Helsinki University of Technology
Telecommunications Software and Multimedia Laboratory
URL: http://www.tcm.hut.fi/~harri
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