execvp()

[Xelinis]

Hey guys, doing a command interpreter for Operating Systems 1 but I can't seem to get execvp to work.

execvp( "ls", NULL );


The PATH variable checks out just fine. Just what am I doing wrong here exactly?

[WW]

Hey guys, doing a command interpreter for Operating Systems 1 but I can't seem to get execvp to work.

What have you tried? What happened? What error messages did you get?

I just tried the simplest C code that I could think of that uses that command you showed, and it worked fine:


#include <unistd.h>

int main(int argc, char *argv[])
{
execvp("ls",NULL);
return 0;
}

[Xelinis]

Did you try it in C or C++? I'm trying to use this in C.

[escapee]

Are you remembering to include the necessary header (unistd.h) like WW has?
And have you installed the build-essential package?

[WW]

C, with the gcc compiler.

[Zugzwang]

Xelinis, you didn't answer WW's question: What happened?

BTW, Xelinis, please try the following example:

#include <unistd.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
execvp("ls",NULL);
printf("\nHello world\n");
return 0;
}

This one works perfectly here. Note that it doesn't say "Hello World" when executing. But this is correct! Look at the man page (http://opengroup.org/onlinepubs/007908799/xsh/exec.html) of execvp to see why. Maybe this is not what you expected and you may want to use system() instead?