Linux Certif

Toute la documentation sur la certification Linux LPI

write

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write - ¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿ (file descriptor) ¤Ë½ñ¤­¹þ¤à

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#include <unistd.h>

ssize_t write(int fd, const void *buf, size_t count);

ÀâÌÀ

write() ¤Ï buf ¤Ç¼¨¤µ¤ì¤ë¥Ð¥Ã¥Õ¥¡¤«¤éºÇÂç count ¥Ð¥¤¥È¤Þ¤Ç¤ò¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿ fd ¤Ë¤è¤Ã¤Æ»²¾È¤µ¤ì¤ë¥Õ¥¡¥¤¥ë¤Ø¤È½ñ¤­¹þ¤à¡£ POSIX ¤Ï write() ¤¬¹Ô¤Ê¤ï¤ì¤¿¸å¤Ë¼Â¹Ô¤·¤¿ read(2) ¤¬ ¿·¤·¤¤¥Ç¡¼¥¿¤òÊÖ¤¹¤³¤È¤òÍ׵ᤷ¤Æ¤¤¤ë¡£ Á´¤Æ¤Î¥Õ¥¡¥¤¥ë¡¦¥·¥¹¥Æ¥à (file system) ¤¬ POSIX ½àµò¤Ç¤Ï¤Ê¤¤ÅÀ¤ËÃí°Õ¤¹¤ë¤³¤È¡£

ÊÖ¤êÃÍ

À®¸ù¤·¤¿¾ì¹ç¡¢½ñ¤­¹þ¤Þ¤ì¤¿¥Ð¥¤¥È¿ô¤¬ÊÖ¤µ¤ì¤ë (¥¼¥í¤Ï²¿¤â½ñ¤­¹þ¤Þ¤ì¤Ê¤«¤Ã¤¿¤³¤È¤ò¼¨¤¹)¡£ ¥¨¥é¡¼¤Ê¤é¤Ð -1 ¤¬ÊÖ¤µ¤ì¡¢errno ¤¬Å¬ÀÚ¤ËÀßÄꤵ¤ì¤ë¡£

count ¤¬ 0 ¤Ç¡¢ fd ¤¬Ä̾ï¤Î¥Õ¥¡¥¤¥ë (regular file) ¤ò»²¾È¤·¤Æ¤¤¤ë¾ì¹ç¡¢ write() ¤Ï¸å½Ò¤Î¥¨¥é¡¼¤Î¤¤¤º¤ì¤«¤ò¸¡½Ð¤·¤¿¾ì¹ç¡¢¼ºÇÔ¤òÊÖ¤¹¤³¤È¤¬¤¢¤ë¡£ ¥¨¥é¡¼¤¬¸¡½Ð¤µ¤ì¤Ê¤«¤Ã¤¿¾ì¹ç¤Ï¡¢ 0 ¤òÊÖ¤·¡¢Â¾¤Ë²¿¤Î±Æ¶Á¤âÍ¿¤¨¤Ê¤¤¡£ count ¤¬ 0 ¤Ç¡¢ fd ¤¬Ä̾ï¤Î¥Õ¥¡¥¤¥ë°Ê³°¤Î¥Õ¥¡¥¤¥ë¤ò»²¾È¤·¤Æ¤¤¤ë¾ì¹ç¡¢ ¤½¤Î·ë²Ì¤Ïµ¬Äꤵ¤ì¤Æ¤¤¤Ê¤¤¡£

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EAGAIN

O_NONBLOCK ¤ò»ÈÍѤ·¤ÆÈóÄä»ß (non-blocking) I/O ¤¬ÁªÂò¤µ¤ì¤Æ¤¤¤ë¤¬¡¢ ½ñ¤­¹þ¤ß¤¬¶Ø»ß (block) ¤µ¤ì¤¿¡£

EBADF

fd ¤¬Í­¸ú¤Ê¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¤Ç¤Ê¤¤¤«½ñ¤­¹þ¤ß¤Î¤¿¤á¤Ë¥ª¡¼¥×¥ó (open) ¤µ¤ì¤Æ¤¤¤Ê¤¤¡£

EFAULT

buf ¤¬¥¢¥¯¥»¥¹²Äǽ¤Ê¥¢¥É¥ì¥¹¶õ´Ö (address space) ¤Î³°¤Ë¤¢¤ë¡£

EFBIG

¼ÂÁõÄêµÁ¤ÎºÇÂç¥Õ¥¡¥¤¥ë¥µ¥¤¥º¤Þ¤¿¤Ï¥×¥í¥»¥¹¤Î¥Õ¥¡¥¤¥ë¥µ¥¤¥ºÀ©¸Â¤ò Ķ¤¨¤Æ¥Õ¥¡¥¤¥ë¤Ë½ñ¤­¹þ¤â¤¦¤È¤·¤¿¡£ ¤Þ¤¿¤Ïµö²Ä¤µ¤ì¤¿¥ª¥Õ¥»¥Ã¥ÈÃͤ賦¤òĶ¤¨¤¿Àè¤Î°ÌÃÖ¤Ë ½ñ¤­¹þ¤â¤¦¤È¤·¤¿¡£

EINTR

²¿¤Î¥Ç¡¼¥¿¤â½ñ¤«¤Ê¤¤´Ö¤Ë¥·¥°¥Ê¥ë¤Ë¤è¤Ã¤Æ³ä¤ê¹þ¤Þ¤ì¤¿ (interrupt)¡£

EINVAL

fd ¤¬½ñ¤­¹þ¤ß¤¬ÉÔŬÀڤʥª¥Ö¥¸¥§¥¯¥È¤ò»²¾È¤·¤Æ¤¤¤ë¡£ ¤â¤·¤¯¤Ï¡¢¥Õ¥¡¥¤¥ë¤¬ O_DIRECT ¥Õ¥é¥°¤ò»ØÄꤷ¤Æ¥ª¡¼¥×¥ó¤µ¤ì¤Æ¤¤¤ë¤¬¡¢ buf ¤Ë»ØÄꤵ¤ì¤¿¥¢¥É¥ì¥¹¡¢ count ¤Ë»ØÄꤵ¤ì¤¿ÃÍ¡¢ ¸½ºß¤Î¥Õ¥¡¥¤¥ë¥ª¥Õ¥»¥Ã¥È¤Î¤¤¤º¤ì¤«¤Î ¥¢¥é¥¤¥ó¥á¥ó¥È¤¬ÉÔŬÀڤǤ¢¤ë¡£

EIO

inode ¤Î½¤ÀµÃæ¤ËÄã¥ì¤Ù¥ë (low-level) I/O ¥¨¥é¡¼¤¬È¯À¸¤·¤¿¡£

ENOSPC

fd ¤Ë¤è¤Ã¤Æ»²¾È¤µ¤ì¤ë¥Õ¥¡¥¤¥ë¤ò´Þ¤à¥Ç¥Ð¥¤¥¹ (device) ¤Ë½½Ê¬¤Ê¶õ¤­¤¬¤Ê¤¤¡£

EPIPE

fd ¤¬¥Ñ¥¤¥× (pipe) ¤«¥½¥±¥Ã¥È (socket) ¤ËÀܳ¤µ¤ì¤Æ¤ª¤ê¡¢ ¤½¤ÎÈ¿ÂЦ (Æɤ߹þ¤ß¦) ¤¬¥¯¥í¡¼¥º (close) ¤µ¤ì¤Æ¤¤¤ë¡£ ¤³¤ì¤¬È¯À¸¤·¤¿¾ì¹ç¤Ë¤Ï¡¢½ñ¤­¹þ¤ß¤ò¹Ô¤Ê¤¦¥×¥í¥»¥¹¤Ï SIGPIPE ¥·¥°¥Ê¥ë (signal)¤â¼õ¤±¤ë¡£ (¤·¤¿¤¬¤Ã¤Æ¡¢¥×¥í¥°¥é¥à¤¬¤³¤Î¥·¥°¥Ê¥ë¤òÊá³Í (catch)¡¢¶Ø»ß (block)¡¢Ìµ»ë (ignore) ¤·¤¿¾ì¹ç¤Î¤ß¡¢write ¤ÎÊÖ¤êÃͤò»²¾È¤Ç¤­¤ë)

fd ¤ËÀܳ¤µ¤ì¤¿¥ª¥Ö¥¸¥§¥¯¥È¤Ë¤è¤Ã¤Æ¤Ï¡¢Â¾¤Î¥¨¥é¡¼¤¬µ¯¤³¤ë¤«¤â¤·¤ì¤Ê¤¤¡£

½àµò

SVr4, 4.3BSD, POSIX.1-2001.

SVr4 ¤Ç¤Ï write ¤¬³ä¤ê¹þ¤Þ¤ì¤ë¤È¡¢¥Ç¡¼¥¿¤¬½ñ¤­¹þ¤Þ¤ì¤ëľÁ°¤Ç¤Ï¤Ê¤¯¡¢ ¤½¤Î»þÅÀ¤Ç EINTR ¤¬Ê֤롣

Ãí°Õ

write() ¤¬À®¸ù¤·¤ÆÊ֤äƤ­¤Æ¤â¡¢¥Ç¡¼¥¿¤¬¥Ç¥£¥¹¥¯¤Ëµ­Ï¿¤µ¤ì¤¿¤³¤È¤ò Êݾڤ¹¤ë¤â¤Î¤Ç¤Ï¤Ê¤¤¡£ ¼ÂºÝ¡¢¥Ç¡¼¥¿¤Î¤¿¤á¤Î¥¹¥Ú¡¼¥¹¤¬³ÎÊݤµ¤ì¤¿¤³¤È¤¹¤éÊݾڤµ¤ì¤Ê¤¤¤È¤¤¤¦ ¥Ð¥°¤Ã¤Ý¤¤¼ÂÁõ¤â¤¢¤ë¡£ ¤³¤ì¤ò³Î¼Â¤Ë¤¹¤ëÍ£°ì¤ÎÊýË¡¤Ï¡¢ Á´¤Æ¤Î¥Ç¡¼¥¿¤ò write ¤·¤¿¸å¤Ë fsync(2) ¤ò¸Æ¤Ó½Ð¤¹¤³¤È¤Ç¤¢¤ë¡£

´ØÏ¢¹àÌÜ

close(2), fcntl(2), fsync(2), ioctl(2), lseek(2), open(2), pwrite(2), read(2), select(2), writev(2), fwrite(3)