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dup sample

Last updated at 2015-04-04Posted at 2015-04-04


  #include <unistd.h>
  #include <fcntl.h>
  #include <sys/types.h>

  int screen;
  int file;
  int flags;
  mode_t mode;
  char data[] = "ok\n";
 
  /* 新規書き込み */
  flags |= O_WRONLY;
  flags |= O_TRUNC;
  flags |= O_CREAT;
  flags |= O_CLOEXEC;

  /* 0664 */
  mode |= S_IWUSR;
  mode |= S_IWGRP;

  /* 標準出力をオープン */ 
  screen = open("/dev/stdout", flags, mode); 

  /* 通常ファイルをオープン */
  file = open("hoge", flags, mode);
 
  /* 標準出力のディスクリプタと通常ファイルのディスクリプタを同期 */
  dup2(file, screen);

  /* 標準出力をクローズ */
  close(screen);
 
  /* この処理は通常ファイルへ書き込まれる */
  write(file, daa, sizeof data);

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