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DUP
Section: Linux Programmer's Manual (2)Updated: 21 August 1994
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dup, dup2 - ¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼¤òÊ£À½¤¹¤ë½ñ¼°
#include <unistd.h> int dup(int oldfd); int dup2(int oldfd, int newfd);
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dup ¤È dup2 ¤Ï¡¢¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼ oldfd ¤ÎÊ£À½¤òºî¤ë¡£dup ¤Þ¤¿¤Ï dup2 ¤¬À®¸ù¤òÊÖ¤·¤¿¾ì¹ç¤Ë¤Ï¡¢ ¸Å¤¤¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼¤È¿·¤·¤¤¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼¤ÏƱ¤¸¤â¤Î¤È¤·¤Æ »È¤¦¤³¤È¤¬¤Ç¤¤ë¡£ ¤½¤ì¤é¤Ï¥í¥Ã¥¯(lock)¡¢¥Õ¥¡¥¤¥ë°ÌÃ֥ݥ¤¥ó¥¿¡¼¡¢ ¥Õ¥é¥°¤ò¶¦Í¤¹¤ë¡£ Î㤨¤Ð¡¢ÊÒÊý¤Î¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼¤Î ¥Õ¥¡¥¤¥ë°ÌÃÖ¤¬ lseek »ÈÍѤ·¤ÆÊѹ¹¤µ¤ì¤¿¾ì¹ç¡¢¡¢¤â¤¦ÊÒÊý¤Î°ÌÃÖ¤âÊѲ½¤¹¤ë¡£ ¤·¤«¤·¤Ê¤¬¤é¡¢¤Õ¤¿¤Ä¤Î¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼¤Ï¼Â¹Ô»þ¥¯¥í¡¼¥º(close-on-exec) ¥Õ¥é¥°¤ò¶¦Í¤·¤Æ¤¤¤Ê¤¤¡£
dup ¤Ï»ÈÍѤµ¤ì¤Æ¤¤¤Ê¤¤ºÇ¾®¤ÎÃͤΥǥ£¥¹¥¯¥ê¥×¥¿¡¼¤ò¿·¤·¤¤¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼ ¤È¤·¤Æ»ÈÍѤ¹¤ë¡£
dup2 ¤Ï oldfd ¤ÎÊ£À½¤È¤·¤Æ newfd ¤òºîÀ®¤¹¤ë¡£É¬Íפʤé¤ÐºÇ½é¤Ë newfd ¤ò¥¯¥í¡¼¥º(close)¤¹¤ë¡£
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dup ¤È dup2 ¤Ï¿·¤·¤¤¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼¤òÊÖ¤¹¡£¥¨¥é¡¼¤Î¾ì¹ç¤Ï -1 ¤òÊÖ¤¹¡£ (¤½¤Î»þ¡¢ errno ¤ËŬÀÚ¤ÊÃͤ¬ÀßÄꤵ¤ì¤ë¡£)¥¨¥é¡¼
- EBADF
- oldfd ¤¬¥ª¡¼¥×¥ó¤µ¤ì¤¿¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼¤Ç¤Ê¤¤¤«¡¢ newfd ¤¬¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼¤È¤·¤Æµö¤µ¤ì¤ëÈϰϤ«¤é³°¤ì¤Æ¤¤¤ë¡£
- EMFILE
- ¥×¥í¥»¥¹¤¬¤¹¤Ç¤Ë¥ª¡¼¥×¥ó¤Ç¤¤ëºÇÂç¿ô¤Þ¤Ç¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼ ¤ò³«¤¤¤Æ¤¤¤Æ¡¢¤µ¤é¤Ë¿·¤·¤¤¤â¤Î¤ò³«¤³¤¦¤È¤·¤¿¡£
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newfd ¤¬ÈϰϤòĶ¤¨¤¿»þ¤ËÊÖ¤µ¤ì¤ë¥¨¥é¡¼¤Ï¡¢ dup2 ¤È fcntl(..., F_DUPFD, ...) ¤Ç¤Ï°Û¤Ã¤Æ¤¤¤ë¡£ dup2 ¤¬ F_DUPFD ¤ÈƱ¤¸¤è¤¦¤Ë EINVAL ¤òÊÖ¤¹¥¹¥Æ¥à¤â¤¢¤ë¡£½àµò
SVr4, SVID, POSIX, X/OPEN, BSD 4.3. SVr4 ¤Ë¤Ï¾¤Ë EINTR,ENOLINK ¥¨¥é¡¼¾õÂ֤ε½Ò¤¬¤¢¤ë¡£POSIX.1 ¤Ë¤Ï¾¤Ë EINTR ¤¬¤¢¤ë¡£´ØÏ¢¹àÌÜ
fcntl(2), open(2), close(2)