Calling a shell command in C code

The code below worked. It showed all of the parameters of the shell command ifconfig. Now, I would like to stored its output in a variable as in
string_result = system(string1);
The above code does not work.

1) What command that I need to run to stored the result of a shell command in a variable in C program ?
======================================

#include <stdio.h>
#include <stdlib.h>

int system(const char *string1);

int main()
{
char string1[] = "ifconfig";

system(string1);
return(0);
}

pipe the output of the command to a file and then read in the file.

Hi, i have the same problem you posted. Would you please let me know when you find the solution?

I found this command: _system_r(), and it is supposed to work but when linking with gcc linker it returns "udefined reference to '_system_r'". Do you know why?

Please, stay in touch.

Thanx
Luis Molina

I tried answering earlier, but we had terrible access problems at work. As a result, the sample code I had written is lost. So now I'm at home and late for bed, so I'll be terse.

The piping should be done with the popen function call. You pass it a string with the command and the open option (just like fopen). Also like fopen, it returns a FILE* which you then use to fread or fgets just as you would from a text file on disk. The only difference would be that you use pclose to close the pipe when you are done.

For example:
FILE* fp = popen("ifconfig","r"); // open a shell and run ifconfig, then read its output.

The command string can also contain options and parameters.

That should get you started.

/* Hola, esta es una solucion que yo encontre a ese problema que tambien tube. */

#include<stdio.h>
#include<string.h>

main()
{

// FILE *popen(const char *orden, const char *tipo);
FILE *f;
int i;
char cadena;
char cad[300];

f = popen("ping -w 1 127.0.0.1 ","r"); //>> /root/TesisNetsaint/Pesca/result.txt

for ( i=0 ; i <=280 ; i++) // 280 = Size of the result
{
//printf( "%c", fgetc(f) );
cad[i] = fgetc(f) ;
} // Bueno!!!!

cad[i]= '\o' ;
printf("%s",cad);

if( strstr(cad,"0 packets received") ){
printf("Host DOWN");
}else{
printf("Host UP");
}
}

¿No debe ser cero? Como '\0'.

Shouldn't that be a zero, as in '\0'?