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/*gcc uebung05.c -Wall -ansi -o uebung05.out*/
#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/stat.h>

char* mystdin(){
  int  strlen = 4;                            /*string lenght*/
  char *str = malloc(strlen * sizeof(char));  /*input string*/
  char c;                                     /*new char*/
  int counter = 0;                            /*position neuer char*/
  while((c = getchar()) != '\n'){             /*zeile einlesen*/
    if(counter >= strlen)                     /*falls länge überschritten*/
      str = realloc(str, (strlen += 4) * sizeof(char)); /* mache platz für 4 neue Zeichen*/
    str[counter++] = c;                       /*füge neuen cahr hinzu*/
  }
  str = realloc(str, (counter++) * sizeof(char));
  str[counter-1] = '\0';                      /*beende string*/
  return str;
}

int main(void)
{
  pid_t pid, wpid;
  int status = 0;
  int newSTDIN = 0;
  int newSTDOUT = 0;
  char* input = NULL;
  char* output = NULL;
  char* cmd;
  char* params;
  char* lcmd=mystdin();
  printf("lcmd:\"%s\"\n", lcmd);
  char* temp=strchr(lcmd,'<');
  if(temp!=NULL){
      input=lcmd;
      *(temp-1)='\0';
      temp++;
      cmd=temp;
  }
  else
      cmd=lcmd;
  output=strchr(cmd,'>');
  if(output!=NULL){
      *output='\0';
      output++;
  }
  while(*output==' ')
    *output++;
  while(*cmd==' ')
    *output++;
  params=strchr(cmd,' ');
  if(params!=NULL){
      *params='\0';
      params++;
  }
  printf("input:\"%s\"\n", input);
  printf("output:\"%s\"\n", output);
  printf("cmd:\"%s\"\n", cmd);
  printf("params:\"%s\"\n", params);
  if((pid=fork()) < 0)
    perror("fork error");
    else if(pid == 0) {
          if(input != NULL){
            newSTDIN = open(input, O_RDONLY);
                dup2(newSTDIN, STDIN_FILENO);
                close(newSTDIN);
          }
          if(output != NULL){
            newSTDOUT = open(output, O_RDONLY);
                dup2(newSTDOUT, STDIN_FILENO);
                close(newSTDOUT);
          }
          return execlp(cmd,cmd,params,NULL);
    }else {
      wpid = wait(&status);
      printf("Exit status of %d was %d (%s)\n", (int)wpid, status, (status == 0)? "OK" : "ERROR");
      /*free?*/
    }
        }