I have already soved this. How do I delete this entry.
I guess I have to erase all text, but that would leave a dangling entry with no topic.

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root:~# gcc -o test-fscanf2 test-fscanf2.c

test-fscanf2.c: In function `find_ethernet_card_address':
test-fscanf2.c:32: warning: return makes integer from pointer without a cast

It is complaining on line 32
32 return (ethernet_mac_address);

When I commented line 32, I can compile, but when I run
it gives me "segmentation fault" error.

I wanted to return ethernet_mac_address, so I am back with
returning a character array from a function call.

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


char find_ethernet_card_address(var1, var2, var3, var4, ethernet_mac_address)
char var1[17], var2[17], var3[17], var4[17];
char ethernet_mac_address[17];
{
FILE *file_pointer, *fopen();

file_pointer = popen("ifconfig", "r");
fscanf(file_pointer, "%s%s%s%s%s", &var1, &var2, &var3, &var4, &ethernet_mac_address);

printf ("var1 = %s\n", var1);
printf ("var2 = %s\n", var2);
printf ("var3 = %s\n", var3);
printf ("var4 = %s\n", var4);
printf ("ethernet_mac_address = %s\n",
ethernet_mac_address);
fclose (file_pointer);
32 return (ethernet_mac_address);
}

main()
{

char var1[17];
char var2[17];
char var3[17];
char var4[17];
char ethernet_mac_address[17];
int result = 99;

find_ethernet_card_address(var1, var2, var3, var4, ethernet_mac_address);

}

Just a question, but if you're printing out the variable and assigning the string in main() the value of it, do you need to return it? Seems to me you'd already have the value...

Probably because the address get's distroyed after the function ends.

This is call by reference
You neednot return the value

was:
char find_ethernet_card_address(var1, var2, var3, var4, ethernet_mac_address)

MUST:
char *find_ethernet_card_address(var1, var2, var3, var4, ethernet_mac_address)

might I suggest that you leave it... it might help other people who are having similar problems