catコマンドを作る！ stdio版

mcat.c

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

int main(int argc, char *argv[]){
  int i;

  if(argc < 2){
    fprintf(stderr, "%s: file name not given\n", argv[0]);
    exit(1);
  }

  for(i=1; i<argc; i++){
    FILE *f;
    int c;

    f = fopen(argv[i], "r");
    if(!f){
      perror(argv[i]);
      exit(2);
    }
    while((c = fgetc(f)) != EOF){
      if(putchar(c) < 0) exit(3);
    }
    fclose(f);
  }
  exit(0);
}