Thread: system call with user input

after my first week of reading and doing some tutorials i decided to try my own program. i run a liux machine with enlightenment desktop. so i decided to try a menu c program to make some things easy for me. i know bash shell scripting and wrote a nice script, but want to import it to the C lanquage.

i am trying to call the whois command with the domain name from the user input for the domain name or ip address. the problem is after calling the whois -h whois.arin.net command i need the doman or ip to follow to be able to look it up. please help with suggestions. if i can learn this, that will help me out a lot with other programs i want to take from the bash script to the C language. this is just one of many that will be linked to one large c program.

here is the code.

do i use the gets or scanf or would it be better to use a pointer. ?????????

#include <stdio.h>
#include <stdlib.h>
#define exit 4

int menu(void); /* main menu */
int arin(void); /* 1. arin.net */
int apnic(void); /* 2. apnic.net */
int ripe(void); /* 3. ripe.net */
char input[100];

int main()
{
int choice = 0;
while (choice != exit)
{
choice = menu();
if (choice == 1)
arin();
else
if (choice == 2)
apnic();
else
if (choice == 3)
ripe();
}
printf("\n\nThank you for using linshell\n\n");

return 0;
}

/* arin.net */
int arin(void)
{
printf("Domain or IP: ");
gets(input);
system("whois -h whois.arine.net %d",input);
}


/* apnic.net */
int apnic(void)
{
printf("Domain or IP: ");
}


/* ripe.net */
int ripe(void)
{
printf("Domain or IP: ");
}



/* display the main menu */
int menu(void)
{
int option = 0;
do
{
printf("\n\n");
printf("\t1. arin\n");
printf("\t2. apnic\n");
printf("\t3. ripe\n");
printf("\t4. exit");
printf("\n\n");
printf(" Select: ");
scanf("%d", &option);
}

while (option < 1 || option > 4);
return option;
}

after reading many websites and doing the tutorials i will be getting a book.

thanks,

enlinux

just read the board about getting color in text. works great. from know on, i don't think i will be doing any more shell scripting. ok so maybe both. ha ha ha ha

First of all: use CODE TAGS

> gets(input);

This function is WRONG, never use it.
Instead use the fgets function (read the BUGS section on the fgets man page)

fgets(input, sizeof(input), stdin)

Remember that the fgets function will also store the newline character.

> scanf("%d", &option);

Better check the return value of scanf.
Another option to do this is read the input with the fgets function and then use the sscanf function to get the option.

still can't get it. looked on the message board and on google. just will have to stay with the shell script i wrote for now.

it works when i use printf but not with system

lets say i want to use the linux command ping to test my server is up.

[code] /*

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

int main()

{
char ipadd;

printf("enter ip address: ");
scanf("%d", &ipadd);
system("ping -c 4 %s",ipadd);

return 0;
}

this will not compile. i have messed around and tried everything.

maybe this is over my head, since i have been reading about c for 1 week. but it can't be that hard. i can write it in perl and shell scripting.

can some one give me a very simple example. i will take it from there. or give me a website with a tutorial on it.

thanks,

enlinux

About the problem with system(), try something like that:

Code:

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

int main(void) {
    char target[] = " 10.200.1.1";
    char whole[100] = "ping -t";
    
    strcat(whole,target);
    printf("%s\n",whole);
    system(whole);
    system("PAUSE");
    return 0;
}

i finally got it to work. thanks for all your help.