c - Redirecting one file to another using dup2 and strtok -

i have write program, in need use strtok , dup2 redirect 1 file another, need have user put command cat < file1 > file2, not shell, instead using program. that's why need strtok. , reason program doesn't work because of that, because don't understand how strtok works. found similar program on internet, take ls command , redirect file. that's it. program more complicated. mean, would've been easier in shell cat < file1 > file2, reason want way. so, anyways, here have far (here combined have found on internet had before. had similar user go ls or ls -l. simple stuff. harder, me, @ least.)

 #include <fcntl.h>  #include <unistd.h>  #include <stdio.h>  #include <errno.h>  #include <sys/wait.h>  #include <string.h>    int main() {      pid_t pid;      char line[256];      char *args[129];      int i;      int fd;      int status;      char *temp;       while (1) {             printf(">");             if (fgets(line, 256, stdin) == 0) {                  exit(0);         }             else {             pid = fork();             if (pid == 0) {                 = 0;                 temp = strtok("<",line);                 while (temp != null) {                    args[i++] = temp;                    temp = strtok(">",line);                    args[i] = '\0';                  }                 fd = open("hello", o_rdonly);                 dup2(fd, stdin_fileno);                 fd = open("world", o_wronly|o_creat|o_trunc, s_irwxu);                 dup2(fd, stdout_fileno );                 close(fd);                 execvp(args[0], args);                 }                 else {                   close(fd);                   wait(&status);               }             }        }      } 

any appreciated.

besides backwards strtok arguments, there other problems.

• the parent process closes fd never opened (it's uninitialized variable there, you're closing random fd may not exist)
• the child process 2 opens , 2 dup2's 1 close. you're leaking fd.
• hardcoded filenames
• you single "<" have loop detecting multiple ">"s
• lack of <stdlib.h> exit()
• who thinks s_irwxu more readable 0700?

and if you're aiming approximate behavior of real shell, should @ least ignore whitespace around redirection operators.