User input to linux command in C

Question

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <string.h>

void getCommand(char* cmd, char** arg_list)
{
pid_t child_pid;

child_pid = fork();

if (child_pid == 0)
{
    execvp (cmd, arg_list);
    fprintf(stderr, "error");
    abort();
}

}

int main(void)
{

printf("Type the command\n");

char *arg_list[] = {NULL, NULL, NULL, NULL, NULL, NULL, NULL};

char cmd[20];
char delim[2] = " ";
char *token;

scanf("%[^\n]", cmd);

token = strtok(cmd, delim);

while (token != NULL)
{
    arg_list[0] = token;
    token = strtok(NULL, cmd);
}

getCommand (arg_list[0], arg_list);
return 0;
}

What I'm trying to achieve here is I want to read user input, which should be a linux command, and then execute the command. It seems that I can't use strtok to split my string. I'm kinda lost, thanks for the help.

paddy got your main problem. You should get in the habit of checking errno. Printing "error" isn't going to tell you much. Also you might want to have the parent wait on the child. — Duck
– Duck, Commented May 13, 2013 at 2:17

paddy · Accepted Answer · 2013-05-13 02:10:12Z

1

Your successive calls to strtok are wrong. You need to pass the delimiters. Also, you are only writing to the first element of your array. Try this:

int n = 0;
while (token != NULL && n < 7)
{
    arg_list[n++] = token;
    token = strtok(NULL, delim);
}

answered May 13, 2013 at 2:10

paddy

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