Programming c++ to run commands in a particualr directory

iwasapenguin · 01-12-2008, 01:28 AM

Okay newbie to code I may be but I´m writing an IDE like program at the moment.
The problem is that I need a way to get the program to run a command that the user has
specified at the push of a button, and as you can imagine make won´t do so well when it is running in /usr/bin and the targets are in /home/$USER/generic_program.

Can somebody explain the code needed to make sure that the command is run in the right directory?

PS: if there is a KDE realted method that would be optimal.

Uncle_Theodore · 01-12-2008, 01:52 AM

Is man chdir what you want?

iwasapenguin · 01-12-2008, 09:21 PM

Quote:

Originally Posted by Uncle_Theodore

Is man chdir what you want?

Perhaps... I´ll have to test it on my own computer (I post of a Damn Small box that doesn´t even have man!

Also, what I forgot is even a bigger matter is how to make these commands run inside of an xterm or konsole (as you can probably tell I´ve bitten of more than I can chew here).

Uncle_Theodore · 01-12-2008, 11:34 PM

It would be better if you'd specify what you want a little more precise.
What I gathered so far is that you want to call a command from inside a C or C++ program, and this command should be called from a particular directory and in a terminal. This is relatively easy. You get to the proper directory by doing chdir, you execute a command by doing popen() or exec and you specify that your command should run in a terminal by calling this terminal with the corresponding option.

For example,

Code:

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

int main()
{
  if(chdir("/home/kot/Desktop") != -1)
    printf("Successfully changed directory to Desktop!\n");
  else printf("Error changing directory!\n");

  if(fork())
    execl("/usr/bin/xterm", "-e", "/usr/bin/emacs", (char*)0);
  else 
    printf("Close the pop-up window first!\n");

  wait(NULL);
  
  return 0;
}

osor · 01-13-2008, 07:12 PM

Quote:

Originally Posted by Uncle_Theodore

This is relatively easy. You get to the proper directory by doing chdir, you execute a command by doing popen() or exec and you specify that your command should run in a terminal by calling this terminal with the corresponding option.

The canonical technique is to do child process setup (such as chdir) after the fork but before the exec. That way, you don’t mess up your own process’ state (i.e., the directory is changed in the child but left alone in the parent).