{"id":54,"date":"2010-04-17T21:31:21","date_gmt":"2010-04-18T06:31:21","guid":{"rendered":"\/blog\/?p=54"},"modified":"2023-09-21T09:41:21","modified_gmt":"2023-09-21T00:41:21","slug":"unix-select-poll-multiplex-%ec%84%9c%eb%b2%84-%ea%b5%ac%ed%98%84%ec%9c%84%ed%95%9c-%ec%9e%90%eb%a3%8c-1","status":"publish","type":"post","link":"https:\/\/hasu0707.duckdns.org\/blog\/?p=54","title":{"rendered":"Unix Select Poll - Multiplex \uc11c\ubc84 \uad6c\ud604\uc704\ud55c \uc790\ub8cc 1"},"content":{"rendered":"\n

unix select \uc640 poll<\/FONT><\/SPAN><\/B><\/SPAN><\/P>\n

<\/SPAN><\/o:p><\/SPAN><\/B> <\/FONT><\/P>\n

2. \ud30c\uc77c \ud578\ub4e4\ub9c1 \uc77c\ubc18 (\ud30c\uc774\ud504\uc640 \uc18c\ucf13 \ud3ec\ud568)
<\/SPAN> <\/SPAN><\/FONT><\/FONT> 2.1 \ub2e4\uc911 \uc5f0\uacb0(multiple connection)\uad00\ub9ac\ub294 \uc5b4\ub5bb\uac8c \ud558\ub294\uac00?
<\/SPAN>   <\/SPAN><\/FONT><\/FONT> 2.1.1 select()\ub294 \uc5b4\ub5bb\uac8c \uc0ac\uc6a9\ud558\ub294\uac00?
<\/SPAN>   <\/SPAN><\/FONT><\/FONT> 2.1.2 poll()\uc740 \uc5b4\ub5bb\uac8c \uc0ac\uc6a9\ud558\ub294\uac00?
<\/SPAN>   <\/SPAN><\/FONT><\/FONT> 2.1.3 select\ub098 poll\ucc98\ub7fc \ub3d9\uc2dc\uc5d0 SysV IPC\ub97c \uc0ac\uc6a9\ud560 \uc218 \uc788\ub294\uac00?
<\/SPAN> <\/SPAN><\/FONT><\/FONT> 2.2 \ubc18\ub300\ucabd \uc5f0\uacb0\uc774 \ub04a\uacbc\ub294\uc9c0 \uc54c\uc218 \uc788\uc2b5\ub2c8\uae4c?
<\/SPAN> <\/SPAN><\/FONT><\/FONT> 2.3 \ub514\ub809\ud1a0\ub9ac\ub97c \uc77d\ub294 \uac00\uc7a5 \uc88b\uc740 \ubc29\ubc95\uc740?
<\/SPAN> <\/SPAN><\/FONT><\/FONT> 2.4 \uc5b4\ub5a4 \ub2e4\ub978 \uc0ac\ub78c\uc774 \ud30c\uc77c\uc744 \uc5f4\uc5c8\ub294\uc9c0 \uc54c \uc218 \uc788\uc2b5\ub2c8\uae4c?
<\/SPAN> <\/SPAN><\/FONT><\/FONT> 2.5 \uc5b4\ub5bb\uac8c \ud30c\uc77c\uc5d0 \ub77d\uc744 \uac78 \uc218 \uc788\uc2b5\ub2c8\uae4c?
<\/SPAN> <\/SPAN><\/FONT><\/FONT> 2.6 \ud30c\uc77c\uc774 \ub2e4\ub978 \ud504\ub85c\uc138\uc2a4\uc5d0 \uc758\ud574 \uc5c5\ub370\uc774\ud2b8 \ub418\uc5c8\ub294\uc9c0 \uc5b4\ub5bb\uac8c \uc54c \uc218 \uc788\uc2b5\ub2c8\uae4c?
<\/SPAN> <\/SPAN><\/FONT><\/FONT> 2.7 'du' \ud504\ub85c\uadf8\ub7a8\uc740 \uc5b4\ub5bb\uac8c \uc791\ub3d9 \ud558\ub294 \uac83\uc785\ub2c8\uae4c?
<\/SPAN> <\/SPAN><\/FONT><\/FONT> 2.8 \ud30c\uc77c\uc758 \ud06c\uae30\ub294 \uc5b4\ub5bb\uac8c \uc54c \uc218 \uc788\uc2b5\ub2c8\uae4c?
<\/SPAN> <\/SPAN><\/FONT><\/FONT> 2.9 \uc258\uc5d0\uc11c \ucc98\ub7fc '~'\ub97c \ud30c\uc77c \uc774\ub984\uc5d0\uc11c \uc5b4\ub5bb\uac8c \ud655\uc7a5\ud560 \uc218 \uc788\uc2b5\ub2c8\uae4c?
<\/SPAN> <\/SPAN><\/FONT><\/FONT> 2.10 named pipe\uc778 (FIFOs)\ub97c \uac00\uc9c0\uace0 \ubb34\uc5c7\uc744 \ud560 \uc218 \uc788\ub294\uac00?
<\/SPAN>   <\/SPAN><\/FONT><\/FONT> 2.10.1 named pipe\uac00 \ubb61\ub2c8\uae4c?
<\/SPAN>   <\/SPAN><\/FONT><\/FONT> 2.10.2 named pipe\ub97c \uc5b4\ub5bb\uac8c \ub9cc\ub4ed\ub2c8\uae4c?
<\/SPAN>   <\/SPAN><\/FONT><\/FONT> 2.10.3 named pipe\ub97c \uc5b4\ub5bb\uac8c \uc0ac\uc6a9\ud569\ub2c8\uae4c?
<\/SPAN>   <\/SPAN><\/FONT><\/FONT> 2.10.4 NFS\ub97c \ud1b5\ud574\uc11c named pipe\ub97c \uc0ac\uc6a9\ud560 \uc218 \uc788\uc2b5\ub2c8\uae4c?
<\/SPAN>   <\/SPAN><\/FONT><\/FONT> 2.10.5 \ub3d9\uc2dc\uc5d0 \uc5ec\ub7ec \ud504\ub85c\uc138\uc2a4\uac00 \ud30c\uc774\ud504\uc5d0 \uc4f8 \uc218 \uc788\uc2b5\ub2c8\uae4c?
<\/SPAN>   <\/SPAN><\/FONT><\/FONT> 2.10.6 \uc751\uc6a9\ud504\ub85c\uadf8\ub7a8\uc5d0\uc11c\uc758 named pipe \uc0ac\uc6a9


2. \ud30c\uc77c \ud578\ub4e4\ub9c1 \uc77c\ubc18 (\ud30c\uc774\ud504\uc640 \uc18c\ucf13 \ud3ec\ud568)
******************************************************

\ub2e4\uc74c\uc5d0 \uc788\ub294 \uc18c\ucf13 FAQ\ub3c4 \uac19\uc774 \ubcf4\ub77c:

`http:\/\/kipper.york.ac.uk\/~vic\/sock-faq\/'

`ftp:\/\/rtfm.mit.edu\/pub\/usenet\/news.answers\/unix-faq\/socket'

2.1 \ub2e4\uc911 \uc811\uc18d(multitple connection)\uc740 \uc5b4\ub5bb\uac8c \uad00\ub9ac\ud558\ub098?
=======================================

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>\ub098\ub294 \ud558\ub098 \uc774\uc0c1\uc758 \uc7a5\uce58\ub97c \ubaa8\ub2c8\ud130\ub9c1 \ud574\uc57c \ud55c\ub2e4. \uadf8\ub4e4 \ubaa8\ub450\ub97c \uc5b4\ub5bb\uac8c \uad00\ub9ac \ud560\uc218 \uc788\ub294\uac00?

select() \ub610\ub294 poll()\uc744 \uc0ac\uc6a9\ud558\ub77c.

select()\ub294 BSD\uc5d0 \uc758\ud574\uc11c \uc18c\uac1c \ub41c \uac83\uc774\uace0 poll()\uc740 System V Stream\uc5d0 \uc758\ud574 \ub9cc\ub4e4\uc5b4 \uc9c4 \uac83\uc774\ub2e4.
\uc21c\uc218 BSD\uc2dc\uc2a4\ud15c\uc740 \uc5ec\uc804\ud788 poll\ub85c\ub294 \ubd80\uc871\ud558\uace0 \uc608\uc804 SVR3\ub294 select()\ub97c \uac00\uc9c0\uace0 \uc788\uc9c0 \uc54a\uace0, SVR4\uc5d0 \uc11c select()\uac00 \ucd94\uac00 \ub418\uc5c8\ub2e4. \uadf8\ub9ac\uace0 Posix.1g\uc5d0\uc11c \uc774 \ub458\uc740 \ud45c\uc900\uc73c\ub85c \ucc44\ud0dd\ub418\uc5c8\ub2e4.

select()\uc640 poll()\uc740 \uc791\uc740 \ubd80\ubd84\uc744 \uc81c\uc678 \ud558\uace0\ub294 \uc6d0\ucc9c\uc801\uc73c\ub85c \uac19\uc740 \uc77c\uc744 \ud55c\ub2e4. \ub458\ub2e4 \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uc758 \ubb36\uc74c\uc5d0 \uc5b4\ub5a0\ud55c \uc774\ubca4\ud2b8\uac00 \ubc1c\uc0dd \ud558\ub294 \uac83\uc744 \ud14c\uc2a4\ud2b8\ud558\uba70,<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc120\ud0dd\uc801\uc73c\ub85c \uc2dc\uac04\uc744 \uc635\uc158\uc73c\ub85c \uc8fc\uc5b4 \uc77c\uc815 \uc2dc\uac04\ub3d9\uc548 \uc774\ubca4\ud2b8\uac00 \uc77c\uc5b4\ub098\uae38 \uae30\ub2e4\ub9b4 \uc218\ub3c4 \uc788\ub2e4.

\uc911\uc694\ud55c \uac83\uc740 select()\ub098 poll() \ub458\ub2e4 \uc77c\ubc18 \ud30c\uc77c\uc5d0\uc11c\ub294 \uc544\ubb34\ub7f0 \uc758\ubbf8\uac00 \uc5c6\ub2e4\ub294 \uac83\uc774\ub2e4. \uc774\ub4e4\uc740 \uc18c\ucf13\uc774\ub098 \ud30c\uc774\ud504, \ud130\ubbf8\ub110 \uc7a5\uce58, \ub610\ub294 \ubb38\uc790 \uc7a5\uce58 \ub4f1\uc5d0\uc11c \uc0ac\uc6a9 \uac00\ub2a5\ud558\ub2e4. \ubb3c\ub860 \uc2dc\uc2a4\ud15c \uc758\uc874\uc801\uc774\uc9c0\ub9cc.

2.1.1 select()\ub294 \uc5b4\ub5bb\uac8c \uc0ac\uc6a9 \ud558\ub294\uac00?
----------------------------

select()\ud558\uae30 \uc704\ud55c \uc778\ud130\ud398\uc774\uc2a4\ub294 'fd_set'\uc758 \uac1c\ub150\uc5d0<\/SPAN> <\/SPAN> \uc8fc\ub85c \uae30\ubc18\uc744 \ub454\ub2e4. \uc774\uac83\uc740 \ud30c\uc77c<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ub514\uc2a4\ud06c\ub9bd\ud130\uc758 \ubaa8\uc784\uc778\ub370 \ubcf4\ud1b5 bit \ubca1\ud130\ub85c\uc11c \uad6c\ud604 \ub41c\ub2e4. \uc608\uc804\uc5d0\ub294 \ubcf4\ud1b5 \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uac00 32\ubcf4\ub2e4 \uc791\uc558\uc5c8\ub2e4. \uadf8\ub9ac\uace0 \uadf8 \ubaa8\uc784\uc5d0 \ub123\uae30 \uc704\ud574 int\ud615\uc744 \uc0ac\uc6a9 \ud588\uc5c8\ub2e4. \uadf8\ub7ec\ub098 \uc694\uc998\uc740 \uadf8 \ubcf4\ub2e4 \ub354 \ub9ce\uc740 \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\ub97c \uc0ac\uc6a9 \ud560 \uc218 \uc788\ub2e4. \uadf8\ub798\uc11c \uc774 fd_set\uc744 \ub2e4\ub8e8\uae30 \uc704\ud574 \ud45c\uc900 \ub9e4\ud06c\ub85c\ub97c \uc0ac\uc6a9\ud558\ub294 \uac83\uc774 \uc911\uc694\ud558\ub2e4\uace0 \ud558\uaca0
\ub2e4.

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>fd_set set;
<\/SPAN>    <\/SPAN>FD_ZERO(&set);<\/SPAN>   <\/SPAN><\/FONT><\/FONT> \/* empties the set *\/
<\/SPAN>    <\/SPAN>FD_SET(fd,&set)<\/SPAN>  <\/SPAN><\/FONT><\/FONT>\/* adds FD to the set *\/
<\/SPAN>    <\/SPAN>FD_CLR(fd,&set);<\/SPAN> <\/SPAN><\/FONT><\/FONT> \/* removes FD from the set *\/
<\/SPAN>    <\/SPAN>FD_ISSET(fd,&set)<\/SPAN> <\/SPAN><\/FONT><\/FONT> \/* true if FD is in the set *\/

\ub300\ubd80\ubd84\uc758 \uacbd\uc6b0 fdset\uc774 \ubaa8\ub4e0 \ubc94\uc704\uc758 \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\ub97c \ub2e4\ub8f0<\/SPAN> <\/SPAN> \uc218 \uc788\ub3c4\ub85d \ud655\uc2e0 \ud560 \uc218 \uc788\ub3c4\ub85d \ud558\ub294 \uac83\uc740 \uc2dc\uc2a4\ud15c\uc758 \ucc45\uc784\uc774\ub2e4. \uadf8\ub7ec\ub098 \uba87\uba87 \uacbd\uc6b0\uc5d0 \uc5ec\ub7ec\ubd84\ub4e4\uc740 FD_SETSIZE\ub9e4\ud06c\ub85c\ub97c \ubbf8\ub9ac<\/SPAN> <\/SPAN> \uc815\uc758\ud574 \ub193\uc544\uc57c \ud55c\ub2e4. \uc774\uac83\ub3c4 \ubb3c\ub860 \uc2dc\uc2a4\ud15c \uc758\uc874\uc801\uc774\uc9c0\ub9cc \uc77c\ub2e8 \uc5ec\ub7ec\ubd84\uc758 \uc2dc\uc2a4\ud15c\uc758 select()\uc5d0 \ub300\ud55c \ub9e4\ub274\uc5bc<\/SPAN> <\/SPAN> \ud398\uc774\uc9c0\ub97c \ucc38\uc870 \ud558\ub77c. \ub610\ud55c \uba87\uba87 \uc2dc\uc2a4\ud15c\uc740 1024\uac1c<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc774\uc0c1\uc758 \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\ub97c \ud578\ub4e4\ub9c1 \ud558\ub294\ub370 \ubb38\uc81c\uac00 \uc788\ub294 \uacbd\uc6b0\ub3c4 \uc788\ub2e4.

select\ud558\uae30 \uc704\ud55c \uae30\ubcf8\uc801\uc778 \uc778\ud130\ud398\uc774\uc2a4\ub294 \ub2e4\uc74c\uacfc \uac19\ub2e4:

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>int select(int nfds, fd_set *readset,
<\/SPAN>                         <\/SPAN><\/FONT><\/FONT> fd_set *writeset,
<\/SPAN>                         <\/SPAN><\/FONT><\/FONT> fd_set *exceptset, struct timeval *timeout);

`nfds'
<\/SPAN>    <\/SPAN>\uac80\uc0ac\ud560 \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uc758 \uac1c\uc218\uc774\ub2e4. \uc774\uac83\uc740 \ubc18\ub4dc\uc2dc fdset\uc758<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uc758 \ucd5c\ub300\uac12\ubcf4\ub2e4 \ucee4\uc57c \ud558\uba70, \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uc758 \uc2e4\uc81c \uac12\uc740 \uc544\ub2c8\ub77c\ub294 \uc810\uc744 \uc54c\uc544\ub46c\uc57c \ud55c\ub2e4.

`readset'
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>\uc77d\uae30 \uac00\ub2a5\uc778\uc9c0\ub97c \uc2dc\ud5d8\ud558\uae30 \uc704\ud55c \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uc758 \ubaa8\uc784(set)

`writeset'
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>\uc4f0\uae30 \uac00\ub2a5\uc778\uc9c0\ub97c \uc2dc\ud5d8\ud558\uae30 \uc704\ud55c \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uc758 \ubaa8\uc784(set)

`exceptfds'
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>\uc608\uc678 \uc0c1\ud0dc\uc5d0 \ub300\ud55c \uc2dc\ud5d8\uc744 \ud558\uae30 \uc704\ud55c \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uc758 \ubaa8\uc784(set)
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>(error\ub294 \uc608\uc678 \uc0c1\ud0dc\uac00 \uc544\ub2c8\ub2e4)

`timeout'
<\/SPAN>    <\/SPAN>\ubb34\ud55c\uc815 \uc2dc\uac04\uc744<\/SPAN> <\/SPAN> \uc704\ud574 NULL<\/SPAN>  <\/SPAN>\uac12\uc774\uba70, \ub610\ub294 \ucd5c\ub300<\/SPAN> <\/SPAN> \ub300\uae30<\/SPAN> <\/SPAN> \uc2dc\uac04\uc744 \uc9c0\uc2dc\ud55c\ub2e4.(<\/SPAN> <\/SPAN> \ub9cc\uc57d<\/SPAN> <\/SPAN><\/FONT><\/FONT> tv_sec\uacfc
tv_usec\ubaa8\ub450\uac00 0\uc774\ub77c\uba74 \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uc758 \uc0c1\ud0dc\ub294 poll\ub41c\ub2e4. \uadf8\ub7ec\ub098<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uadf8 \ud638\ucd9c\uc740 \uacb0\ucf54 \ube14\ub85d\ub418\uc9c0 \uc54a\ub294\ub2e4.

\ud638\ucd9c\uc740 'ready'\ub41c \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uc758 \uc22b\uc790\ub97c \ub418\ub3cc\ub9b0\ub2e4. \uadf8\ub9ac\uace0 \uc138 \uac1c\uc758 fdset\uc740 \ubcc0\uacbd\ub418\ub294\ub370 ready \uc0c1\ud0dc\uc778 \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\ub9cc set\uc5d0<\/SPAN> <\/SPAN> \ub0a8\uac8c \ub41c\ub2e4. \ub9ac\ud134\ub41c \ud30c\uc77c<\/SPAN> <\/SPAN> \ub514\uc2a4\ud06c\ub9bd\ud130 \ubb36\uc74c\uc744 \ud14c\uc2a4\ud2b8 \ud558\uae30<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc704\ud574 FD_ISSET \ub9e4\ud06c\ub85c\ub97c \uc0ac\uc6a9\ud558\ub77c.

\uc5ec\uae30 \uac04\ub2e8\ud55c \uc0d8\ud50c \ud504\ub85c\uadf8\ub7a8\uc774 \uc788\ub2e4. \uc774 \ud504\ub85c\uadf8\ub7a8\uc740<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ud558\ub098\uc758 \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uac00 \uc77d\uae30 \uac00\ub2a5\uc778\uc9c0 \ud14c\uc2a4\ud2b8 \ud55c\ub2e4.

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>int isready(int fd)
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>int rc;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>fd_set fds;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>struct timeval tv;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>FD_ZERO(&fds);
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>FD_SET(fd,&fds);
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>tv.tv_sec = tv.tv_usec = 0;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>rc = select(fd+1, &fds, NULL, NULL, &tv);
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>if (rc < 0)
<\/SPAN>          <\/SPAN><\/FONT><\/FONT>return -1;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>return FD_ISSET(fd,&fds) ? 1 : 0;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>}

\uc6b0\ub9ac\ub294 \uc6b0\ub9ac\uac00 \ud14c\uc2a4\ud2b8\uc5d0 \uad00\uc2ec \uc5c6\uc744 \ub54c\ub294 fdset\uc5d0 NULL\uc744 \ub123\uc744 \uc218\ub3c4 \uc788\ub2e4\ub294 \uac83\uc744 \uc54c\uc544\ub450\ub77c.

2.1.2 poll()\uc740 \uc5b4\ub5bb\uac8c \uc0ac\uc6a9\ud558\ub098?
--------------------------

Poll\uc740 struct pollfd\uc758 \ub9ac\uc2a4\ud2b8\ub85c \ud3ec\uc778\ud130\ub97c \uc785\ub825 \ubc1b\ub294\ub2e4. \uc774\uac83\uc740 \ub514\uc2a4\ud06c\ub9bd\ud130 \uc774\uace0 \uc5ec\ub7ec\ubd84\uc774<\/SPAN> <\/SPAN> \uc800\uc7a5\ub41c \uac83\uc5d0 \ub300\ud558\uc5ec poll\ud558\uae30\ub97c \ubc14\ub77c\ub294 \uc774\ubca4\ud2b8\uc774\ub2e4. \uc774 \uc774\ubca4\ud2b8\ub294 \uc2a4\ud2b8\ub7ed\ucdb0\uc758 \uc774\ubca4\ud2b8 \ud544\ud2b8\uc5d0\uc11c bitwise\ub9c8\uc2a4\ud06c\ub97c \ud1b5\ud558\uc5ec \uc9c0\uc815\ub41c\ub2e4. \uadf8 \uc2a4\ud2b8\ub7ed\ucdb0\uc758 \uad6c\uc131\uc694\uc18c\ub294 \ud6c4\uc5d0 \uc5b4\ub5a4 \ubc1c\uc0dd\ub418\uc5b4 \uc5ec\ub7ec\ubd84\uc5d0\uac8c \uc804\ub2ec\ub420 \uc774\ubca4\ud2b8\ub85c \uc800\uc7a5\ub41c\ub2e4. SVR4\uc5d0\uc11c \ub9e4\ud06c\ub85c\ub294 poll.h\uc5d0 \uc758\ud574 \uc815\uc758 \ub418\uace0(\uc544\ub9c8 \uadf8 \uc774\uc804\ubc84\uc804\ub3c4 \uadf8\ub7f4 \ub4ef<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ud558\ub2e4) \ud544\ub4dc\uc5d0\uc11c \uc774\ubca4\ud2b8\ub97c \uc815\uc758\ud558\ub294\ub370 \uc0ac\uc6a9\ub41c\ub2e4. \ud0c0\uc784\uc544\uc6c3\uc740 \ubc00\ub9ac\ucd08\ub85c \uc9c0\uc815\ub418\ub294\ub370 \uc9c0\uc6d0\ub418\ub294 type\ud615\uc740 \uc815\uc218\ud615\uc774\ub2e4.(\uc815\uc218\ud615\uc740 \ucc38 \ud63c\ub780\uc2a4\ub7f0 \ud0c0\uc785\uc774\uae34 \ud558\ub2e4.) \ud0c0\uc784\uc544\uc6c3\uc774 0\uc774\uba74 poll()\uc740 \uc989\uc2dc \ub9ac\ud134\ub418\uace0, \ub9cc\uc57d \ud0c0\uc784\uc544\uc6c3\uc774 -1\uc774\uba74 poll\uc740 \uc5b4\ub5a4 \uc774\ubca4\ud2b8\uac00 \ubc1c\uc0dd\ud560\ub54c\uae4c\uc9c0 \uc77c\uc2dc\uc815\uc9c0(suspend)\ub41c\ub2e4.

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>struct pollfd {
<\/SPAN>        <\/SPAN>int fd;<\/SPAN>       <\/SPAN><\/FONT><\/FONT> \/* The descriptor. *\/
<\/SPAN>        <\/SPAN>short events;<\/SPAN> <\/SPAN><\/FONT><\/FONT> \/* The event(s) is\/are specified here. *\/
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>short revents; \/* Events found are returned here. *\/
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>};

select\uc640 \uc544\uc8fc \ube44\uc2b7\ud558\uac8c\ub3c4, \ub9ac\ud134\uac12\uc774 \uc591\uc758 \uc22b\uc790\uc77c \ub54c \uc774\ub294 \uc5bc\ub9c8\ub098 \ub9ce\uc740 \ub514\uc2a4\ud06c\ub9bd\ud130\uac00 \uc870\uac74 \uc774\ubca4\ud2b8 \uc694\uad6c\uc744 \ub9cc\uc871\ud558\ub294\uc9c0\ub97c \ub098\ud0c0\ub0b8\ub2e4. \uc694\uad6c\ub41c \uc774\ubca4\ud2b8\uac00 \uc9c0\uc815\ub41c \uc2dc\uac04\uc5d0 \uc5c6\uc744 \uacbd\uc6b0\uc5d4<\/SPAN> <\/SPAN><\/FONT><\/FONT> 0\uc774 \ub9ac\ud134\ub41c\ub2e4. \ub9cc\uc57d \uc74c\uc218\uac00 \ub9ac\ud134\ub418\uba74 \uc774\uac83\uc744 \uc5d0\ub7ec\ub97c \ub73b\ud558\uae30 \ub54c\ubb38\uc5d0 \ubc18\ub4dc\uc2dc \uc989\uc2dc \uc5d0\ub7ec\ub97c \uccb4\ud06c \ud574\uc57c \ud55c\ub2e4.

\ub9cc\uc57d \uc774\ubca4\ud2b8\uac00 \ubc1c\uacac\ub418\uc9c0 \uc54a\uc73c\uba74 \uc774\ubca4\ud2b8\uac00 clear\ub418\uace0 \uc5ec\ub7ec\ubd84\ub4e4\uc744<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc704\ud574 \uc774\uac83\uc740 \ub354 \uc774\uc0c1 \ud544\uc694 \uc5c6\uac8c \ub41c\ub2e4.

\ub9ac\ud134\ub41c \uc774\ubca4\ud2b8\ub4e4\uc740 \uadf8 \uc774\ubca4\ud2b8\ub97c \ud3ec\ud568\ud558\uace0 \uc788\ub294\uc9c0 \ud14c\uc2a4\ud2b8 \ub41c\ub2e4.

\uc608\uc81c\ub97c \ubcf4\uba74..:

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>\/* \uc77c\ubc18 \ub370\uc774\ud130 \ud639\uc740 \ub192\uc740 priority\ub97c \uac16\ub294 \ub370\uc774\ud130\uc5d0 \ub300\ud55c \ub450 \uac1c\uc758 \ub514\uc2a4\ud06c\ub9bd\ud130\uc5d0\uc11c Poll\ud55c\ub2e4.
<\/SPAN>       <\/SPAN><\/FONT><\/FONT> \ub9cc\uc57d \uc5b4\ub5a4 \ubc1c\uacac\ub41c \uac83\uc774 \uc801\ub2f9\ud55c \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\ub85c \ud568\uc218 handle()\uc744 \ud638\ucd9c \ud558\uba74
<\/SPAN>       <\/SPAN><\/FONT><\/FONT> \ud0c0\uc784\uc544\uc6c3\uc744 \uac78\uc9c0 \ub9d0\uace0, \uc5d0\ub7ec \uc77c \uacbd\uc6b0\uc5d0\ub9cc \ub610\ub294 \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uc911\uc758 \ud558\ub098\uac00 hang up
<\/SPAN>       <\/SPAN><\/FONT><\/FONT> \uc77c \uacbd\uc6b0\uc5d0\ub9cc \uadf8\ub9cc \ub450\ub3c4\ub85d \ud558\ub77c *\/
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#define NORMAL_DATA 1
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#define HIPRI_DATA 2
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>int poll_two_normal(int fd1,int fd2)
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>struct pollfd poll_list[2];
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>int retval;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>poll_list[0].fd = fd1;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>poll_list[1].fd = fd2;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>poll_list[0].events = POLLIN|POLLPRI;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>poll_list[1].events = POLLIN|POLLPRI;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>while(1)
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>retval = poll(poll_list,(unsigned long)2,-1);
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>\/* \uc774 \uacbd\uc6b0\uc5d0 Retval\uc740 \ud56d\uc0c1 0 \ub610\ub294 -1 \ubcf4\ub2e4 \ud074 \uac83\uc774\ub2e4.
<\/SPAN>               <\/SPAN><\/FONT><\/FONT> \uc65c\ub0d0\uba74 \uc6b0\ub9ac\ub294 \uadf8\uac83\uc774 \ube14\ub85d\ud0b9 \ud558\ub294 \ub3d9\uc548 \uc218\ud589\ud558\uae30 \ub54c\ubb38\uc774\ub2e4
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>*\/
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>if(retval < 0)
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>                <\/SPAN><\/FONT><\/FONT>fprintf(stderr,\"Error while polling: %s\\n\",strerror(errno));
<\/SPAN>                <\/SPAN><\/FONT><\/FONT>return -1;
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>}
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>if(((poll_list[0].revents&POLLHUP) == POLLHUP) ||
<\/SPAN>               <\/SPAN><\/FONT><\/FONT> ((poll_list[0].revents&POLLERR) == POLLERR) ||
<\/SPAN>               <\/SPAN><\/FONT><\/FONT> ((poll_list[0].revents&POLLNVAL) == POLLNVAL) ||
<\/SPAN>               <\/SPAN><\/FONT><\/FONT> ((poll_list[1].revents&POLLHUP) == POLLHUP) ||
<\/SPAN>               <\/SPAN><\/FONT><\/FONT> ((poll_list[1].revents&POLLERR) == POLLERR) ||
<\/SPAN>               <\/SPAN><\/FONT><\/FONT> ((poll_list[1].revents&POLLNVAL) == POLLNVAL))
<\/SPAN>              <\/SPAN><\/FONT><\/FONT>return 0;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>if((poll_list[0].revents&POLLIN) == POLLIN)
<\/SPAN>              <\/SPAN><\/FONT><\/FONT>handle(poll_list[0].fd,NORMAL_DATA);
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>if((poll_list[0].revents&POLLPRI) == POLLPRI)
<\/SPAN>              <\/SPAN><\/FONT><\/FONT>handle(poll_list[0].fd,HIPRI_DATA);
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>if((poll_list[1].revents&POLLIN) == POLLIN)
<\/SPAN>              <\/SPAN><\/FONT><\/FONT>handle(poll_list[1].fd,NORMAL_DATA);
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>if((poll_list[1].revents&POLLPRI) == POLLPRI)
<\/SPAN>              <\/SPAN><\/FONT><\/FONT>handle(poll_list[1].fd,HIPRI_DATA);
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>}
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>}

2.1.3 select\ub098 poll\ucc98\ub7fc System V IPC\ub3c4 \ub3d9\uc2dc\uc5d0 \uc0ac\uc6a9\ud560 \uc218 \uc788\ub294\uac00?
------------------------------------------------------------

*\uc544\ub1e8* (\uc774\uac83\uc744 \ud5c8\uc6a9\ud558\uae30 \uc704\ud574 \uc9c0\uc800\ubd84\ud558\uace0 \uc2e0\ub8b0\uc131\uc774 \ub5a8\uc5b4\uc9c0 \uad6c\ud604\ub41c AIX\ub97c \uc81c\uc678\ud558\uace0)

\uc77c\ubc18\uc801\uc73c\ub85c System V\uc758 \uba54\uc2dc\uc9c0 \ud050\ub97c \ud568\uaed8 \uc0ac\uc6a9\ud558\uc5ec select\ub098 Poll\uc744 \uc870\ud569\ud558\uc5ec \uc0ac\uc6a9\ud558\ub294\uac74 \ubb38\uc81c\ub97c \uc77c\uc73c\ud0a8\ub2e4. System V IPC \uc624\ube0c\uc81d\ud2b8\ub294 \ud30c\uc77c \ub514\uc2a4\ud06c\ub9bd\ud130\uc5d0 \uc758\ud574<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc81c\uc5b4 \ub418\uc9c0 \uc54a\ub294\ub2e4. \uadf8\ub798\uc11c \uadf8\ub4e4\uc740 select()\ub098 poll()\uc5d0 \uc804\ub2ec \ub420 \uc218 \uc5c6\ub2e4. \uc774\ub7f0 \ucd94\ud55c \ubd80\ubd84(?)\uc774 \ub9ce\ub2e4.

<\/SPAN>  <\/SPAN><\/FONT><\/FONT>- \uc2dc\uc2a4\ud15c V IPC\ub294 \ubc84\ub824 \ubc84\ub824\ub77c! \ud83d\ude42

<\/SPAN>  <\/SPAN><\/FONT><\/FONT>- fork()\ub97c \uc218\ud589\ud55c \ud6c4, \uc790\uc2dd \ud504\ub85c\uc138\uc2a4\ub85c \ud558\uc5ec\uae08 \uc2dc\uc2a4\ud15cV IPC\ub97c \ud578\ub4e4 \ud558\ub3c4\ub85d \ud558\uba74, \ubd80\ubaa8 \ud504\ub85c\uc138\uc2a4\uc640 \uc790\uc2dd \ud504\ub85c\uc138\uc2a4\uac04\uc5d0 \ud30c\uc774\ud504\uc640 \uc18c\ucf13\uc744 \ud1b5\ud558\uc5ec \ud1b5\uc2e0\ud560 \uc218 \uc788\ub294\ub370, \uc774 \ud30c\uc774\ud504\uc640 \uc18c\ucf13\uc740 \ubd80\ubaa8 \ud504\ub85c\uc138\uc2a4\uac00 select()\ud560 \uc218 \uc788\ub2e4.

<\/SPAN>  <\/SPAN><\/FONT><\/FONT>- \uc704\uc5d0 \ucc98\ub7fc\uc740 \uac00\ub2a5\ud558\uc9c0\ub9cc \uc790\uc2dd \ud504\ub85c\uc138\uc2a4\uac00 select()\ud558\uac70\ub098 \ubd80\ubaa8 \ud504\ub85c\uc138\uc2a4\uc640 \uba54\uc2dc\uc9c0 \ud050\ub97c \ud1b5\ud558\uc5ec \ud1b5\uc2e0\ud558\ub294 \uac83\uc740 \uc548\ub41c\ub2e4.

<\/SPAN>  <\/SPAN><\/FONT><\/FONT>- \uac01 \uba54\uc2dc\uc9c0 \ud6c4\uc5d0 \uc5ec\ub7ec\ubd84\uc5d0\uac8c \uc2e0\ud638\ub97c \uc804\ub2ec\ud558\uae30 \uc704\ud574 \uba54\uc2dc\uc9c0\ub97c \uc804\ub2ec\ud558\ub294 \ud504\ub85c\uc138\uc2a4\ub97c \uc815\ub3c8\ud558\ub77c.
\uacbd\uace0\ud558\ub294\ub370 \uc774\ub7ec\ud55c \uad8c\ud55c\uc744 \ud578\ub4e4\ub9c1 \ud558\ub294 \uac83\uc740 \uc0ac\uc18c\ud55c<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc77c\uc774 \uc544\ub2c8\uba70, \uc774\ub7ec\ud55c \ubc29\ubc95\uc744 \uc0ac\uc6a9\ud558\uba74 \uc7a0\uc7ac\uc801\uc73c\ub85c \uba54\uc2dc\uc9c0\ub97c \uc783\uc5b4 \ubc84\ub9ac\uac70\ub098 \ub370\ub4dc\ub77d\uc5d0 \uac78\ub9ac\ub294 \ubb38\uc81c\ub97c \uc77c\uc73c\ud0a4\ub294 \ud504\ub85c\uadf8\ub7a8\uc744 \uc9dc\uae30 \uc27d\ub2e4.

(\ub610\ud55c \ub2e4\ub978 \ubc29\ubc95\ub4e4\ub3c4 \uc874\uc7ac\ud55c\ub2e4.)

2.2 \ubc18\ub300\ucabd \uc5f0\uacb0\uc774 \ub04a\uacbc\ub294\uc9c0 \uc54c\uc218 \uc788\uc2b5\ub2c8\uae4c?
=================================================================

\ub9cc\uc57d \uc5ec\ub7ec\ubd84\uc774 \ud30c\uc774\ud504\ub098 \uc18c\ucf13, FIFO \ub4f1\uc744 \ud1b5\ud574 \uc77d\uc73c\ub824\uace0 \ud55c\ub2e4\uba74, \ubc18\ub300\ucabd \uc5f0\uacb0\uc774 close\ub420 \ub54c \uc5ec\ub7ec\ubd84\uc740 EOF\uba54\uc2dc\uc9c0\ub97c \uc5bb\uc744 \uc218 \uc788\ub2e4.(read()\ud568\uc218\ub294 0\uc744 \ub9ac\ud134\ud55c\ub2e4.) \ub9cc\uc57d \uc5ec\ub7ec\ubd84\uc774<\/SPAN> <\/SPAN> \ud30c\uc774\ud504\ub098 \uc18c\ucf13\ub4f1\uc73c\ub85c write\ud558\ub824\uace0 \ud558\uba74, \uc77d\ub294 \ub3c4\uc911\uc774 \uc0c1\ub300\ud3b8\uc774 close\ud560<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ub54c SIGPIPE \uc2e0\ud638\uac00 \ud504\ub85c\uc138\uc2a4\uc5d0\uac8c \uc804\ub2ec\ub418\uace0 \uc2e0\ud638\uac00 \uce90\uce58\ub418\uc9c0 \uc54a\uc740 \uadf8\uac83\uc744 \uc8fd\uc774\uac8c \ub41c\ub2e4.(\ub9cc\uc57d \uc5ec\ub7ec\ubd84\uc774 \uadf8 \uc2e0\ud638\ub97c \ube14\ub85d\ud558\uac8c \ub418\uba74 write() \ud638\ucd9c\uc740 EPIPE \uc640 \ud568\uaed8 \uc5d0\ub7ec\ub97c \ub9ac\ud134\ud55c\ub2e4.)

2.3 \ub514\ub809\ud1a0\ub9ac\ub97c \uc77d\ub294 \uac00\uc7a5 \uc88b\uc740 \ubc29\ubc95\uc740?
=================================

\uc5ed\uc0ac\uc801\uc73c\ub85c \uc774\ub97c \uc704\ud55c \uc5ec\ub7ec \uac00\uc9c0 \uc778\ud130\ud398\uc774\uc2a4\uac00 \uc874\uc7ac\ud574 \uc654\ub2e4. \uc694\uc998 Posix.1\ud45c\uc900\uc73c\ub85c \uc790\ub9ac\uc7a1\uc740 \uc720\uc77c\ud55c \ud558\ub098\ub294 \uc758 \ud568\uc218\ub97c \uc4f0\ub294 \uac83\uc774\ub2e4.

opendir() \ud568\uc218\ub294 \ud2b9\uc815 \ub514\ub809\ud1a0\ub9ac\ub97c \uc5f4\uba70, readdir()\ud568\uc218\ub294<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uadf8\uac83\uc73c\ub85c \ubd80\ud130 \ub514\ub809\ud1a0\ub9ac \ud45c\uc900\ud654\ub41c \ud3ec\ub9f7\uc73c\ub85c \uc5d4\ud2b8\ub9ac\ub97c \uc77d\uc5b4\ub4e4\uc774\uace0; closedir()\uc740 \ub2eb\ub294\ub2e4. \ub610\ud55c rewinddir(), telldir()\uadf8\ub9ac\uace0 seekdir()\uc744 \uc0ac\uc6a9\ud560 \uc218 \uc788\ub2e4.

\ub9cc\uc57d \uc5ec\ub7ec\ubd84\uc774 \uc640\uc77c\ud2b8\uce74\ub4dc \uc774\ub984\uc744 \uc4f0\uae30 \uc6d0\ud55c\ub2e4\uba74, \ub300\ubd80\ubd84\uc758 \uc2dc\uc2a4\ud15c\uc774 glob()\ud568\uc218\ub97c \uc9c0\uc6d0\ud558\ub2e4\ub294 \uac83\uc744 \uc54c\uc544\ub46c\ub77c. \ub610\ud55c \uc640\uc77c\ub4dc \uce74\ub4dc \uc774\ub984\uc774 \ub9e4\uce6d\ub418\ub294\uc9c0 \ud655\uc778\ud558\ub294 fnmatch()\ud568\uc218\uac00 \uc874\uc7ac\ud558\ub294\uc9c0\ub3c4 \ud655\uc778\ud558\uace0, \ub514\ub809\ud1a0\ub9ac \uc804\uccb4\ub97c \ud6d1\uc5b4 \ub0b4\ub9ac\ub294 ftw()\ud568\uc218\ub3c4 \ubd10\ub77c.

2.4 \ud55c \ud30c\uc77c\uc744 \uc5b4\ub5a4 \uc0ac\ub78c\uc774 \uc5f4\uace0 \uc788\ub294\uc9c0 \uc54c\uc218 \uc788\ub294\uac00?
=======================================================

\uc774\uac83\uc740 \ub610 \ub2e4\ub978 \"Frequently Unanswered Question\"\uc758 \ud55c \ud6c4\ubcf4\uac00 \ub420 \ub4ef \uc2f6\ub2e4. \uc65c\ub0d0\uba74 \uc77c\ubc18\uc801\uc73c\ub85c \uc5ec\ub7ec\ubd84\ub4e4\uc758 \ud504\ub85c\uadf8\ub7a8\uc740 \ub2e4\ub978 \ub204\uac00 \ud30c\uc77c\uc744 \uc5f4\uc5c8\ub294\uc9c0\ub294 \uad00\uc2ec\uc774 \uc5c6\uc744 \uac83\uc774\uae30 \ub54c\ubb38\uc774\ub2e4. \ub9cc\uc57d \uc5ec\ub7ec\ubd84\uc774 \ud30c\uc77c\uc5d0 \ub300\ud55c \ub3d9\uc2dc \uc561\uc138\uc2a4\ub97c \ub2e4\ub8e8\uae38 \uc6d0\ud55c\ub2e4\uba74 locking\uc5d0 \ub300\ud55c \uac83\uc744 \ucc3e\uc544\ubd10\ub77c.

\uc774\uac83\uc740 \uc77c\ubc18\uc801\uc73c\ub85c \ub9d0\ud574\uc11c \ub9e4\uc6b0<\/SPAN> <\/SPAN> \uc5b4\ub824\uc6b4 \uc77c\uc774\ub2e4. fuser\uc640 lsof\uc640<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uac19\uc740 \ud504\ub85c\uadf8\ub7a8\ub4e4\uc774 \uc774\ub7ec\ud55c \uc77c\uc744 \ud574\uc8fc\uae30\ub294 \ud558\uc9c0\ub9cc \ucee4\ub110 \ub370\uc774\ud130\ub97c \ud1b5\ud574\uc11c \uc548\uc88b\uc740 \ubc29\ubc95\uc73c\ub85c \ucc3e\uc544\ub0b4\ub294 \uac83\ub4e4\uc774\uae30 \ub54c\ubb38\uc774\ub2e4.
\uc5ec\ub7ec\ubd84\ub4e4\uc740 \uc774\ub7ec\ud55c \ud504\ub85c\uadf8\ub7a8\uc744 \uc5ec\ub7ec\ubd84\uc758 \ud504\ub85c\uadf8\ub7a8\uc5d0\uc11c \ud638\ucd9c\ud574\uc11c \uc4f8 \ud544\uc694\ub294 \uc5c6\ub2e4. \uc65c\ub0d0\ud558\uba74 \uadf8 \ud30c\uc77c\uc774 \uc5f4\ub824 \uc788\uac74 \uc544\ub2c8\uac74 \uac04\uc5d0 \uadf8 \uc0ac\uc2e4\uc744 \ud655\uc778\ud55c \uadf8 \uc2dc\uc810\uc5d0 \uadf8 \uc0ac\uc2e4 \uc790\uccb4\uac00 \uc4f8\ubaa8 \uc5c6\uac8c \ub418\uae30 \ub54c\ubb38\uc774\ub2e4.

2.5 \ud30c\uc77c\uc5d0 lock\uc744 \uc5b4\ub5bb\uac8c \uac78 \uc218 \uc788\ub294\uac00?
===========================

\uc138\uac00\uc9c0 \ubc29\ubc95\uc774 \uc788\ub2e4. \uadfc\ub370 \ub9cc\uc57d \ub77d\uc744 \uac78\uace0\uc790<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ud558\ub294 \ub370\uc774\ud130 \ud30c\uc77c\uc774 \ub2e4\ub978\uc885\ub958\uc758 \ud504\ub85c\uadf8\ub7a8\uc774 \ub3d9\uc2dc\uc5d0 \uacf5\uc720\ud574\uc11c \uc4f0\ub294 \uc77c\uc774 \uc788\ub2e4\uba74 \uc544\uc8fc \uc138\uc2ec\ud558\uac8c \uc2e0\uacbd\uc744 \uc368\uc11c \ub77d\ud0b9 \uccb4\uc81c\ub97c \uc138\uc6b8 \ud544\uc694\uc131\uc774 \uc788\ub2e4.

\uc2e4\uc81c\ub85c \uba87\uba87 \uc720\ub2c9\uc2a4\ub4e4\uc744 sgid bit\ub97c \ud1b5\ud574\uc11c \ub77d\ud0b9\uc744 \uc704\uc784 \ud558\uace0 \uc788\ub2e4.

\uba87\uba87 \uc5b4\ud50c\ub9ac\ucf00\uc774\uc158\uc740 \ub77d \ud30c\uc77c\uc744<\/SPAN> <\/SPAN> \uc0ac\uc6a9\ud558\uae30\ub3c4 \ud55c\ub2e4.(filename.lock\uacfc \uac19\uc740).<\/SPAN> <\/SPAN> \ub2e8\uc21c\ud788 \uadf8\ub7ec\ud55c \ud30c\uc77c\uc774 \uc874\uc7ac\ud568\uc744 \ud310\ub2e8\ud568\uc73c\ub85c\uc368 \ub77d\uc774 \uac78\ub824\uc788\ub294\uc9c0\ub9cc \ud655\uc778\ud560 \uc218<\/SPAN> <\/SPAN> \uc788\ub3c4\ub85d \ud560 \uc218 \uc788\ub2e4. \uc774 \ubc29\ubc95\uc740<\/SPAN> <\/SPAN> UUCP\uc5d0\uc11c \uc8fc\ub85c \uc0ac\uc6a9\ub418\ub294\ub370 \ubaa8\ub380\uc774 \uc0ac\uc6a9\uc911\uc778\uc9c0\ub97c \uc54c\ub9ac\uae30 \uc704\ud574\uc11c \ub4f1\uc744 \uc704\ud574 \uc4f0\uc778\ub2e4. \uc608\ub97c \ub4e4\uc5b4<\/SPAN> <\/SPAN><\/FONT><\/FONT> PID\ub97c \ub77d \ud30c\uc77c\ub85c \uc4f0\uae30\ub3c4 \ud55c\ub2e4. \uadf8\ub7ec\ub098 \ubb50 \ubb3c\ub860 \uc774\uac83\uc774 \ud655\uc2e4\ud55c \ubc29\ubc95\uc740 \uc544\ub2c8\ub2e4. \uc65c\ub0d0\ud558\uba74 PID\ub294 \ubc18\ubcf5\uc801\uc73c\ub85c \uc21c\ud658\ub418\uae30 \ub54c\ubb38\uc774\ub2e4.

\ub77d\ud0b9 \ud568\uc218\ub294 \ub2e4\uc74c\uacfc \uac19\uc740 \uac83\ub4e4\uc774 \uc788\ub2e4.

<\/SPAN>        <\/SPAN><\/FONT><\/FONT>flock();
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>lockf();
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>fcntl();

flock()\uc740 BSD\uc5d0\uc11c \ucd9c\ubc1c\ud55c \uac83\uc774\uace0 \ud604\uc7ac\ub294 \ub300\ubd80\ubd84\uc758 \uc2dc\uc2a4\ud15c\ub4e4\uc774 \uc9c0\uc6d0\ud558\uace0 \uc788\ub2e4.(\ubb3c\ub860 \uc804\ubd80\ub294 \uc544\ub2c8\uc9c0\ub9cc). \uc774\uac83\uc740 \uac04\ub2e8\ud558\uba74\uc11c\ub3c4 \ud6a8\uacfc\uc801\uc73c\ub85c \ud558\ub098\uc758 \ud638\uc2a4\ud2b8 \uc0c1\uc5d0\uc11c \ub3d9\uc791\ud55c\ub2e4, \ub2e4\ub9cc NFS\uc0c1\uc5d0\uc11c\ub294 \ub3d9\uc791\ud558\uc9c0 \uc54a\ub294\ub2e4. \ub610\ud55c \uc774\uac83\uc740 \ud30c\uc77c \uc804\uccb4\uc5d0 \ub77d\uc744 \uac74\ub2e4. \uc880<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc18d\uc784\uc218\uc801\uc778 \ubc29\ubc95\uc73c\ub85c\uc9c0\ub9cc, PERL\uc5d0\uc11c\ub3c4 \uc774\uac83\uc744 \uad6c\ud604\ud558\uace0 \uc788\ub2e4.

fcntl()\uc740 POSIX \ud638\ud658\uc758 \uc720\uc77c\ud55c<\/SPAN> <\/SPAN> \ub77d\ud0b9 \uba54\ucee4\ub2c8\uc998\uc774\ub2e4. \ub530\ub77c\uc11c \uc720\uc77c\ud55c<\/SPAN> <\/SPAN> \ud638\ud658\uc131\uc774 \uc788\ub294 \ub77d\ud0b9 \uccb4\uacc4\ub77c \ud558\uaca0\ub2e4. \uc774\uac83\uc740 \ub610\ud55c \ub9e4\uc6b0 \uac15\ub825\ud558\uc9c0\ub9cc \uc0ac\uc6a9\ud558\uae30\ub3c4 \uc27d\uc9c0<\/SPAN> <\/SPAN> \uc54a\ub2e4. NFS\uc0c1\ud0dc\uc5d0\uc11c\ub3c4 \uc9c0\uc6d0\ud558\ub294\ub370 fcntl() \uc694\uccad\uc774 NFS\uc11c\ubc84(rpc.lockd)\uc5d0 \uc804\ub2ec\ub418\uc5b4 NFS\uc5d0\uc11c\uc758 \ub77d\ud0b9\ub3c4 \uad6c\ud604\ud558\uace0 \uc788\ub2e4. \uadf8\ub9ac\uace0<\/SPAN> <\/SPAN><\/FONT><\/FONT> fcntl()\uc740 \ub808\ucf54\ub4dc \ub77d\ud0b9\ub3c4 \uc9c0\uc6d0\ud558\uace0 \uc788\ub2e4.

lockf()\ub294 fcntl()\uc744 \ub2e8\uc21c\ud654\ud55c \ud504\ub85c\uadf8\ub798\ubc0d \uc778\ud130\ud398\uc774\uc2a4\uc774\ub2e4.

\uc5b4\ub5a4 \ub77d\ud0b9 \uba54\ucee4\ub2c8\uc998\uc744 \uc4f0\ub358\uc9c0 \uac04\uc5d0, \ub77d\uc774 \uc218\ud589\ub418\uace0 \uc788\uc744\ub54c\ub294 \uc5ec\ub7ec\ubd84\uc758<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ubaa8\ub4e0 \ud30c\uc77c IO\ub97c sync\ud558\ub294 \uac83\uc774 \uc911\uc694\ud558\ub2e4.

<\/SPAN>        <\/SPAN><\/FONT><\/FONT>lock(fd);
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>write_to(some_function_of(fd));
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>flush_output_to(fd); \/* \ucd9c\ub825\uc774 \ubc84\ud37c\ub9c1 \ub418\uc5b4 \uc788\ub294\ub3d9\uc548\uc740 \uacb0\ucf54 unlock\ud560 \uc218 \uc5c6\ub2e4*\/
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>unlock(fd);
<\/SPAN>        <\/SPAN>do_something_else;<\/SPAN>  <\/SPAN><\/FONT><\/FONT>\/* \ub2e4\ub978 \ud504\ub85c\uc138\uc2a4\uac00 \uc5c5\ud14c\uc774\ud2b8 \ud55c\ub2e4.*\/
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>lock(fd);
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>seek(fd, somewhere); \/* \ud30c\uc77c \ud3ec\uc778\ud130\uac00 \uc548\uc804\ud558\uc9c0 \uc54a\uae30 \ub54c\ubb38 *\/
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>do_something_with(fd);
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>...

fcntl()\uc758 \uc720\uc6a9\ud55c \ub77d\ud0b9 \ube44\ucc45! (\ub2e8\uc21c\ud654\ub97c \uc704\ud574 \uc5d0\ub7ec \ud578\ub4e4\ub9c1\uc740 \uc81c\uc678):

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>    <\/SPAN>read_lock(int fd)<\/SPAN>  <\/SPAN><\/FONT><\/FONT>\/* \ud30c\uc77c \uc804\uccb4\uc5d0 \ub300\ud574 \uacf5\uc720 \ub77d\uc744 \uac74\ub2e4 *\/
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>fcntl(fd, F_SETLKW, file_lock(F_RDLCK, SEEK_SET));
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>}
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>    <\/SPAN>write_lock(int fd)<\/SPAN> <\/SPAN><\/FONT><\/FONT> \/* \ud30c\uc77c \uc804\uccb4\uc5d0 \ub300\ud574 \ubc30\uc81c\ub77d\uc744 \uac74\ub2e4*\/
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>fcntl(fd, F_SETLKW, file_lock(F_WRLCK, SEEK_SET));
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>}
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>append_lock(int fd) \/* \uc874\uc7ac\ud558\ub294 \ub808\ucf54\ub4dc\ub4e4\uc5d0 \ub300\ud55c \uc5d1\uc138\uc2a4\ub97c \ub9c9\uae30
<\/SPAN>                       <\/SPAN><\/FONT><\/FONT> \uc704\ud574 \ud30c\uc77c\uc758 \ub05d\uc5d0 \ub77d\uc744 \uac74\ub2e4
<\/SPAN>                       <\/SPAN><\/FONT><\/FONT> *\/
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>fcntl(fd, F_SETLKW, file_lock(F_WRLCK, SEEK_END));
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>}

\uc704\uc758 \uac83\uc5d0 \uc758\ud574 \uc0ac\uc6a9\ub418\ub294 file_lock \ud568\uc218

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>struct flock* file_lock(short type, short whence)
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>static struct flock ret ;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>ret.l_type = type ;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>ret.l_start = 0 ;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>ret.l_whence = whence ;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>ret.l_len = 0 ;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>ret.l_pid = getpid() ;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>return &ret ;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>}

2.6 \ub2e4\ub978 \ud504\ub85c\uc138\uc2a4\uc5d0 \uc758\ud574 \ud30c\uc77c\uc774 \uc5c5\ub370\uc774\ud2b8 \ub418\uc5c8\ub294\uc9c0 \uc54c \uc218 \uc788\ub098?
=========================================================

\uc774\uac83\ub3c4 \uc5ed\uc2dc \"Frequently Unanswered Question\"\uc758 \ud6c4\ubcf4\uac00 \ub420 \ub9cc\ud55c\ub370 \uadf8 \uc774\uc720\ub294 \uc0ac\ub78c\ub4e4\uc774 \uc77c\ubc18\uc801\uc73c\ub85c \ud30c\uc77c\uc774 \ubcc0\uacbd\ub41c \uac83\uc5d0 \ub300\ud55c \ub178\ud2f0\ub97c \ucc3e\uc73c\ub824\uace0 \ud558\ub294\ub370 \uc774\uac83\uc5d0 \ub300\ud55c \ud638\ud658\uc131<\/SPAN> <\/SPAN> \uc788\ub294 \uc194\ub8e8\uc158\uc774 \uc5c6\uae30 \ub54c\ubb38\uc774\ub2e4.(IRIX\uc758 \uacbd\uc6b0\uc5d0\ub294 \ud45c\uc900\uc774 \uc544\ub2cc \ud30c\uc77c \uc561\uc138\uc2a4\uc5d0 \ub300\ud55c \ubaa8\ub2c8\ud130\ub9c1 \ud234\uc774<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc788\uae30\ub294 \ud558\ub2e4, \uadf8\ub7ec\ub098 \ub098\ub294 \ub2e4\ub978 \uacf3\uc5d0 \uc774\ub7f0 \uac83\uc774 \uc788\ub2e4\ub294 \ub9d0\uc744 \ub4e4\uc5b4\ubcf8 \uc801\uc774 \uc5c6\ub2e4.)

\uc77c\ubc18\uc801\uc73c\ub85c \uc5ec\ub7ec\ubd84\ub4e4\uc774 \uc0ac\uc6a9\ud560 \uc218 \uc788\ub294 \uac00\uc7a5 \uc720\uc6a9\ud55c \uac83\uc740 fstat()\uc778\ub370 \uc774\uac83\uc740 \uc624\ubc84\ud5e4\ub4dc \ub54c\ubb38\uc5d0 \ubb34\ucc99 \ub290\ub9ac\ub2e4. \ubcf4\ud1b5\uc740 stat()\ubcf4\ub2e4\ub3c4 \ub354 \ub290\ub9ac\ub2e4. \uc554\ud2bc \uc774 \ud568\uc218\uc5d0\uc11c ctime\uacfc mtime\uc744 \uc774\uc6a9\ud574 \ud30c\uc77c\uc774 \ucd5c\uadfc\uc5d0 \uc5b8\uc81c \uc561\uc138\uc2a4 \ub418\uc5c8\ub294\uc9c0\ub294 \uc54c \uc218 \uc788\uc73c\uba70, \uc0ad\uc81c, link\ub41c\uac70, \uc774\ub984\uc774 \ubc14\ub010\uac83 \ub4f1\uc744 \uc54c \uc218 \uc788\ub2e4.

\uc554\ud2bc \uad73\uc774 \uc774\ub7ec\ud55c \uae30\ub2a5\uc774 \ud544\uc694\ud55c\uc9c0 \ub2e4\uc2dc\ud55c\ubc88 \uc0dd\uac01\ud574 \ubcf4\uae38 \ubc14\ub780\ub2e4.

2.7 du \ud504\ub85c\uadf8\ub7a8\uc774 \uc5b4\ub5bb\uac8c \uc791\ub3d9 \ub418\ub294\uac00?
===================================

du\ub294 \ub2e8\uc21c\ud788 stat()\ud568\uc218\ub97c \ud1b5\ud574 \ub514\ub809\ud1a0\ub9ac\ub97c \ub3cc\uc544\ub2e4\ub2c8\uba74\uc11c \ub514\ub809\ud1a0\ub9ac\uc640 \ud30c\uc77c\uc758 \ube14\ub85d \uc218\ub97c \ub354\ud574\uc11c \uc774\ub97c \ubcf4\uc5ec\uc8fc\ub294 \uc77c\uc744 \ud55c\ub2e4.

\uc5ec\ub7ec\ubd84\uc774 \uc880\ub354 \uc790\uc138\ud55c \uc815\ubcf4\ub97c \uc5bb\uace0 \uc2f6\ub2e4\uba74 \ub2f5\uc740:

<\/SPAN>       <\/SPAN><\/FONT><\/FONT> \uc18c\uc2a4\ub97c \uc0ac\uc6a9\ud574\ub77c. \ud589\uc6b4\uc744 \ube48\ub2e4.

BSD\uc2dc\uc2a4\ud15c(FreeBSD, NetBSD, OpenBSD)\uc5d0 \ub300\ud55c \uc18c\uc2a4\ub294 ftp\uc0ac\uc774\ud2b8\uc5d0 \ub9ce\uc774 \uc788\uace0 GNU\ubc84\uc804\uc5d0 \ub300\ud55c \uc18c\uc2a4\ub294 GNU mirror\uc0ac\uc774\ud2b8\uc5d0 \ub9ce\uc774 \ub3cc\uc544\ub2e4\ub2cc\ub2e4.

2.8 \ud30c\uc77c\uc758 \uc0ac\uc774\uc988\ub97c \uc5b4\ub5bb\uac8c \uc54c \uc218 \uc788\ub294\uac00?
=====================================

stat()\ub97c \uc0ac\uc6a9\ud558\uace0 \ub9cc\uc77c Open\ub41c \ud30c\uc77c\uc774 \uc788\ub2e4\uba74 fstat()\ub97c \uc0ac\uc6a9\ud558\ub77c.

\uc774 \ud638\ucd9c\uc740 \ub370\uc774\ud130 \uad6c\uc870\uccb4\ub97c \ud3ec\ud568\ud558\uace0 \uc788\ub294\ub370 \uc774 \uad6c\uc870\uccb4\uc5d0\ub294 \ud30c\uc77c\uc5d0 \uad00\ub828\ub41c \uc815\ubcf4\ub97c \ubaa8\ub450 \ud3ec\ud568\ud558\uace0 \uc788\ub2e4. \uc608\ub97c \ub4e4\uc5b4 \ud30c\uc77c\uc758 \uc18c\uc720\uc8fc, \uadf8\ub8f9, \ud37c\ubbf8\uc158, \ud06c\uae30, \ucd5c\uadfc \uc811\uadfc\uc2dc\uac04, \ucd5c\uadfc \uc218\uc815\uc2dc\uac04 \ub4f1.

\ub2e4\uc74c \ub8e8\ud2f4\uc740 stat()\uc744 \uc0ac\uc6a9\ud574\uc11c \ud30c\uc77c \ud06c\uae30\ub97c \uad6c\ud558\ub294 \uac83\uc744 \ubcf4\uc5ec\uc900\ub2e4.

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>#include
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>int get_file_size(char *path,off_t *size)
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>      <\/SPAN><\/FONT><\/FONT>struct stat file_stats;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>      <\/SPAN><\/FONT><\/FONT>if(stat(path,&file_stats))
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>return -1;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>      <\/SPAN><\/FONT><\/FONT>*size = file_stats.st_size;
<\/SPAN>      <\/SPAN><\/FONT><\/FONT>return 0;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>}

2.9 \uc258\uc5d0\uc11c\ucc98\ub7fc '~'\ub97c \ud30c\uc77c \uc774\ub984\uc5d0\uc11c\ub3c4 \uc0ac\uc6a9\ud560 \uc218 \uc788\ub294\uac00?
==========================================================

\ud30c\uc77c \uc774\ub984\uc758 \uc2dc\uc791\ubd80\ubd84\uc5d0 \uc624\ub294 '~'\uc5d0 \ub300\ud55c \ud45c\uc900\uc801\uc778 \ud574\uc11d\uc740 \ub2e4\uc74c\uacfc \uac19\ub2e4.
\ub9cc\uc57d \ud63c\uc790 \uc0ac\uc6a9\ub418\uac70\ub098 \ub610\ub294 '\/' \ub2e4\uc74c\uc5d0 \uc624\uac8c \ub418\uba74 \ud604\uc7ac \uc0ac\uc6a9\uc790\uc758 \ud648\ub514\ub809\ud1a0\ub9ac\ub85c \ub300\uccb4 \ub41c\ub2e4. \ub9cc\uc57d \uc0ac\uc6a9\uc790 \uc774\ub984 \ub2e4\uc74c\uc5d0 \uc624\uba74 \uadf8\uac83\uc740 \uc0ac\uc6a9\uc790\uc758 \ud648\ub514\ub809\ud1a0\ub9ac\ub85c \ub300\uccb4\ub41c\ub2e4. \ub9cc\uc57d<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc801\ub2f9\ud55c \ud655\uc7a5(expansion)\uc774 \ubc1c\uacac\ub418\uc9c0 \uc54a\uc73c\uba74 \uc258\uc740 \uadf8 \ud30c\uc77c\uc774\ub984\uc744 \ubcc0\uacbd\uc2dc\ud0a4\uc9c0 \uc54a\uc740\ucc44\ub85c \ub0a8\uaca8\ub454\ub2e4.

\uadf8\ub7ec\ub098 \uc2e4\uc81c\ub85c '~'\ub85c \uc2dc\uc791\ud558\ub294 \ud30c\uc77c \uc774\ub984\uc5d0<\/SPAN> <\/SPAN> \ub300\ud574 \uc8fc\uc758\ud558\ub77c. \ub9c8\uad6c\uc7a1\uc774\uc801\uc778 tilde-expansion\uc740 \uadf8\ub7ec\ud55c \ud30c\uc77c \uc774\ub984\uc744 \ud504\ub85c\uadf8\ub7a8\uc5d0\uac8c \uc9c0\uc815\ud558\ub294\uac78 \uc5b4\ub835\uac8c \ub9cc\ub4e4 \uc218 \uc788\ub2e4.<\/SPAN> <\/SPAN> \ucffc\ud14c\uc774\uc158 \ub9c8\ud06c(\")\ub97c \uc0ac\uc6a9\ud558\uba74 \uc258\uc774 \uadf8\ub7ec\ud55c \ud655\uc7a5 \uac1c\ub150\uc744 \uc0ac\uc6a9\ud558\ub294 \uac83\uc744 \ub9c9\uc544 \uc900\uba70, \ud504\ub85c\uadf8\ub7a8\uc740<\/SPAN> <\/SPAN> tilde(~)\uc790\uccb4\ub97c \ud30c\uc77c \uc774\ub984\uc73c\ub85c \ubcf4\uac8c \ub41c\ub2e4. \uc77c\ubc18\uc801\uc73c\ub85c \ud504\ub85c\uadf8\ub7a8\uc5d0\uac8c \ucee4\ub9e8\ub4dc\ub77c\uc778\uc758 \ud30c\ub77c\ubbf8\ud130\ub85c<\/SPAN> <\/SPAN> \uc804\ub2ec\ub418\ub294 \ud30c\uc77c \uc774\ub984\uc774\ub098 \ud658\uacbd\ubcc0\uc218\uc5d0\uc11c\ub294 tilde\ub97c<\/SPAN>  <\/SPAN>\uc0ac\uc6a9\ud558\uc9c0 \ub9d0\ub77c.<\/SPAN> <\/SPAN> (\ubb3c\ub860,<\/SPAN> <\/SPAN> \ud504\ub85c\uadf8\ub7a8\uc5d0\uc11c<\/SPAN> <\/SPAN> \uc0ac\uc6a9\uc790<\/SPAN> <\/SPAN> \uc785\ub825\uc73c\ub85c \uc0dd\uc131\ub418\ub294<\/SPAN>  <\/SPAN>\ud30c\uc77c \uc774\ub984\uc774\ub098 configuration\ud30c\uc77c\ub85c\ubd80\ud130 \ud30c\uc77c\uc774\ub984\uc744 \uc77d\uc744 \ub54c<\/SPAN> <\/SPAN> \ub4f1\uc740 tilde-expansion\uc744 \uc0ac\uc6a9\ud558\uae30\uc5d0 \uc88b\uc740<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ud6c4\ubcf4\uac10\uc774\ub2e4.)

\uc5ec\uae30 \uc774\ub7ec\ud55c \uc77c\uc744 \ud558\ub3c4\ub85d \ub9cc\ub4e4\uc5b4\uc9c4 \ud45c\uc900 \ubb38\uc790 class\ub97c \uc0ac\uc6a9\ud558\ub294 C++\ucf54\ub4dc\uac00 \uc788\ub2e4.

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>string expand_path(const string& path)
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>if (path.length() == 0 || path[0] != '~')
<\/SPAN>          <\/SPAN><\/FONT><\/FONT>return path;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>const char *pfx = NULL;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>string::size_type pos = path.find_first_of('\/');
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>if (path.length() == 1 || pos == 1)
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>pfx = getenv(\"HOME\");
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>if (!pfx)
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>                <\/SPAN><\/FONT><\/FONT>\/\/ Punt. We're trying to expand ~\/, but HOME isn't set
<\/SPAN>                <\/SPAN><\/FONT><\/FONT>struct passwd *pw = getpwuid(getuid());
<\/SPAN>                <\/SPAN><\/FONT><\/FONT>if (pw)
<\/SPAN>                  <\/SPAN><\/FONT><\/FONT>pfx = pw->pw_dir;
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>}
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>}
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>else
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>string user(path,1,(pos==string::npos) ? string::npos : pos-1);
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>struct passwd *pw = getpwnam(user.c_str());
<\/SPAN>            <\/SPAN><\/FONT><\/FONT>if (pw)
<\/SPAN>              <\/SPAN><\/FONT><\/FONT>pfx = pw->pw_dir;
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>}
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>\/\/ if we failed to find an expansion, return the path unchanged.
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>if (!pfx)
<\/SPAN>          <\/SPAN><\/FONT><\/FONT>return path;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>string result(pfx);
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>if (pos == string::npos)
<\/SPAN>          <\/SPAN><\/FONT><\/FONT>return result;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>if (result.length() == 0 || result[result.length()-1] != '\/')
<\/SPAN>          <\/SPAN><\/FONT><\/FONT>result += '\/';
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>result += path.substr(pos+1);
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>return result;
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>}

2.10 named pipe(FIFOs)\ub97c \uac00\uc9c0\uace0 \ubb34\uc5c7\uc744 \ud560 \uc218 \uc788\ub294\uac00?
============================================

2.10.1 named pipe\uac00 \ubb34\uc5c7\uc778\uac00?
----------------------------

\"named pipe\"\ub294 \uad00\ub828\ub41c \ud504\ub85c\uc138\uc2a4\uac04\uc5d0 \ub370\uc774\ud130\ub97c \uc804\ub2ec\ud558\uae30\uc704\ud55c \ud2b9\ubcc4\ud55c \ud30c\uc77c\uc774\ub2e4.<\/SPAN> <\/SPAN> \ud558\ub098 \ub610\ub294 \uadf8 \uc774\uc0c1\uc758 \ud504\ub85c\uc138\uc2a4\ub4e4\uc774 \uadf8\uac83\uc5d0 \ub370\uc774\ud130\ub97c \uc4f0\uba74<\/SPAN> <\/SPAN> \ub2e4\ub978 \ud504\ub85c\uc138\uc2a4\ub294 \uadf8\uac83\uc744 \uc77d\ub294\ub2e4.<\/SPAN> <\/SPAN> Named pipe\ub294 \ud30c\uc77c \uc2dc\uc2a4\ud15c\uc5d0\uc11c Visible\ud55c \ud30c\uc77c\uc774\uc5b4\uc11c ls\ud504\ub85c\uadf8\ub7a8 \ub4f1\uc73c\ub85c<\/SPAN> <\/SPAN> \ub2e4\ub978 \uc77c\ubc18 \ud30c\uc77c \ucc98\ub7fc \ubcfc<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc218\ub3c4 \uc788\ub2e4.(named pipe\ub294 \ub610\ud55c fifo's\ub77c\uace0\ub3c4 \ubd88\ub9ac\uc6b0\ub294\ub370 \uc774\uac83\uc740 \"First In, First Out\"\uc744 \ub73b\ud55c\ub2e4.)

Named pipe\ub294 \uc77c\ubc18 \ud30c\uc774\ud504\uac00 \ubd80\ubaa8\/\uc790\uc2dd\uac04\uc5d0\ub9cc \uc5f0\uacb0\ud560 \uc218<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc788\ub294\uac83\uc5d0 \ube44\ud574 \uad00\ub828\uc5c6\ub294 \ud504\ub85c\uc138\uc2a4\uac04\uc5d0\ub3c4 \ub370\uc774\ud130\ub97c \uc804\ub2ec\ud558\uace4\ud55c\ub2e4.

\ube44\ub85d \uc2dc\uc2a4\ud15c\uc5d0\uc11c \ubb34\uba85\uc528 pipe\ub294 \uc591\ubc29\ud5a5\uc131\uc774\uc9c0\ub9cc, Named pipe\ub294 \uc808\ub300\uc801\uc73c\ub85c \ud55c\ucabd \ubc29\ud5a5\uc131\uc774\ub2e4.

2.10.2 named pipe\ub97c \uc5b4\ub5bb\uac8c \uc0dd\uc131\ud560 \uc218 \uc788\ub294\uac00?
------------------------------------

\uc778\ud130\ub809\ud2f0\ube0c\ud558\uac8c named pipe\ub97c \ub9cc\ub4e4\uae30 \uc704\ud574\uc11c\ub294 'mknod'\ub610\ub294 'mkfifo'\ub97c \uc2e4\ud589\ud574\uc57c \ud55c\ub2e4.<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc5b4\ub5a4 \uc2dc\uc2a4\ud15c\uc5d0\uc11c\ub294 mknod\uac00 \/etc\ub514\ub809\ud1a0\ub9ac\uc5d0 \uc788\ub2e4. \ub2e4\uc2dc \ub9d0\ud558\uba74 \uc5ec\ub7ec\ubd84\uc758 \ud328\uc2a4\uc5d0 \uc18d\ud574 \uc788\ub2e4\ub294 \ub9d0\uc774\ub2e4. \uc5ec\ub7ec\ubd84\uc758 \ub9e4\ub274\uc5bc \ud398\uc774\uc9c0\ub97c \ubcf4\uba74 \uc790\uc138\ud55c\uac78 \uc54c\uc218 \uc788\ub2e4.

C\ud504\ub85c\uadf8\ub7a8\uc5d0\uc11c named pipe\ub97c \ub9cc\ub4e4\uae30\uc704\ud574 mkfifo()\ud568\uc218\uac00 \uc4f0\uc778\ub2e4.

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>\/* \uba85\uc2dc\uc801\uc73c\ub85c umask\ub97c \uc124\uc815\ud558\uba74 \uc5ec\ub7ec\ubd84\uc740 \uadf8\uac83\uc774 \uc5b4\ub514\uc5d0 \uc874\uc7ac\ud558\ub294\uc9c0 \uc54c\uc218 \uc5c6\ub2e4.*\/
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>umask(0);
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>if (mkfifo(\"test_fifo\", S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP))
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>perror(\"mkfifo\");
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>exit(1);
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>}

mkfifo()\uac00 \uc5c6\uc73c\uba74 mknod()\ub97c \uc0ac\uc6a9\ud574\uc57c \ud55c\ub2e4.

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>\/* set the umask explicitly, you don't know where it's been *\/
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>umask(0);
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>if (mknod(\"test_fifo\",
<\/SPAN>                <\/SPAN><\/FONT><\/FONT>S_IFIFO | S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP,
<\/SPAN>               <\/SPAN><\/FONT><\/FONT> 0))
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>{
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>perror(\"mknod\");
<\/SPAN>        <\/SPAN><\/FONT><\/FONT>exit(1);
<\/SPAN>    <\/SPAN><\/FONT><\/FONT>}

2.10.3 \uc5b4\ub5bb\uac8c named pipe\ub97c \uc0ac\uc6a9\ud558\ub294\uac00?
---------------------------------

pipe\ub97c \uc0ac\uc6a9\ud558\uae30\uc704\ud574\uc11c \uc77c\ubc18 \ud30c\uc77c\ucc98\ub7fc open\ud558\uace0 \uc77c\ubc18 pipe\ucc98\ub7fc read()\uc640 write()\ub97c \uc218\ud589\ud55c\ub2e4.
\uadf8\ub7ec\ub098 open()\uc740 \ube14\ub85d\ub420 \uac83\uc774\ub2e4. \ub2e4\uc74c\uc758 \ub8f0\ub4e4\uc774 \uc801\uc6a9\ub41c\ub2e4.

<\/SPAN>  <\/SPAN><\/FONT><\/FONT>* \ub9cc\uc57d (O_RDWR)\uc758 \ud615\ud0dc, \uc989 \uc77d\uae30,\uc4f0\uae30\uc758 \ud615\ud0dc\ub85c \ud30c\uc77c\uc744 \uc5f4\uba74 \ube14\ub85d\ub418\uc9c0 \uc54a\ub294\ub2e4.

<\/SPAN>  <\/SPAN>* \ub9cc\uc57d \uc77d\uae30\ub85c \uc5f4\uba74(O_RDONLY) \ub2e4\ub978<\/SPAN> <\/SPAN> \ud504\ub85c\uc138\uc2a4\uac00 write\ub85c \uc5f4\ub54c\uae4c\uc9c0 \ube14\ub85d\ub41c\ub2e4. \uadf8\ub7ec\ub098<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ub9cc\uc57d O_NONBLOCK\uc774 \uc9c0\uc815\ub418\uba74 open\uc740\uc131\uacf5\uc801\uc73c\ub85c \ub420 \uac83\uc774\ub2e4.

<\/SPAN>  <\/SPAN>* \ub9cc\uc57d O_WRONLY \ub2e4\ub978 \ud504\ub85c\uc138\uc2a4\uac00 FIFO\ub97c<\/SPAN> <\/SPAN> \uc77d\uae30\ub85c \uc5f4\ub54c\uae4c\uc9c0 \ube14\ub85d\ub41c\ub2e4. \uc774\uac83\ub3c4 \uc5ed\uc2dc<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ub9cc\uc57d \ud30c\uc77c\uc744 \uc5f4 \ub54c O_NONBLOCK\uc774 \uc9c0\uc815\ub418\uba74 \ube14\ub85d\ub418\uc9c0 \uc54a\ub294\ub2e4.

FIFO\ub97c \uc77c\uace0 \uc4f8 \ub54c \uc77c\ubc18 Pipe\ub098 \uc18c\ucf13\uc5d0\uc11c<\/SPAN> <\/SPAN> \uac19\uc774 \uc801\uc6a9\ub418\ub294 \uace0\ub824 \uc0ac\ud56d\uc740 read() \ub4f1\uc758 \ud568\uc218\ub294<\/SPAN> <\/SPAN> \ubaa8\ub4e0 Writer\uac00 \uc0c1\ub300 reader\uac00 \uc5c6\uc5b4\uc11c close\ub418\uac70\ub098 write()\uac00<\/SPAN> <\/SPAN><\/FONT><\/FONT> SIGPIPE\ub97c \ubc1c\uc0dd\uc2dc\ud0a4\uba74 EOF\ub97c \ub9ac\ud134 \uc2dc\ud0a8\ub2e4\ub294 \uac83\uc774\ub2e4. (\ub9cc\uc57d SIGPIPE\uac00 \ube14\ub85d\ub418\uac70\ub098 \ubb34\uc2dc\ub418\uba74 \uadf8 \ud638\ucd9c\uc740 EPIPE\uc758 \uc5d0\ub7ec\ub97c \ub9cc\ub4e4\uba74\uc11c \uc2e4\ud328\ud55c\ub2e4)

2.10.4 NFS\ub97c \ud1b5\ud574\uc11c named pipe\ub97c \uc0ac\uc6a9\ud560 \uc218 \uc788\ub294\uac00?
-----------------------------------------

\uc548\ub41c\ub2e4. NFS\ud504\ub85c\ud1a0\ucf5c\uc5d4 \uc774\ub7ec\ud55c \uae30\ub2a5\uc744 \uc9c0\uc6d0\ud558\uc9c0 \uc54a\ub294\ub2e4.(\uadf8\ub7ec\ub098 NFS\ub85c \ub9c8\uc6b4\ud2b8\ub41c<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ud30c\uc77c \uc2dc\uc2a4\ud15c\uc5d0\uc11c \uac19\uc740 \ud074\ub77c\uc774\uc5b8\ud2b8 \ud504\ub85c\uadf8\ub7a8\uc5d0\uc11c \ud504\ub85c\uc138\uc2a4\uac04 \ud1b5\uc2e0\uc744 \ud558\uae30\uc704\ud574 named pipe\ub97c \uc0ac\uc6a9\ud560 \uc218\ub294 \uc788\ub2e4.)

2.10.5 \uc5ec\ub7ec \ud504\ub85c\uc138\uc2a4\uac00 \ud30c\uc774\ud504\uc5d0 \ub3d9\uc2dc\uc801\uc73c\ub85c write\ud560 \uc218 \uc788\ub098?
---------------------------------------------------------------

\ub9cc\uc57d pipe\uc5d0 \uc4f0\uc5ec\uc9c8 \uac01 \ub370\uc774\ud130\ub4e4\uc774 PIPE_BUF\ubcf4\ub2e4 \uc791\ub2e4\uba74 \uadf8\ub9ac\uace0 \uadf8\ub4e4\uc774 \uc778\ud130\ub9ac\ube0c\ub418\uc9c0 \uc54a\ub294\ub2e4\uba74 \uac00\ub2a5\ud558\ub2e4. \uadf8\ub7ec\ub098 write\uac00 \uc720\uc9c0\ub418\uc9c0 \uc54a\ub294(not preserved) \uc601\uc5ed\uc740 \uc874\uc7ac\ud55c\ub2e4. \ud30c\uc774\ud504\ub85c\ubd80\ud130 \uc77d\uc744 \ub54c, \ube44\ub85d \uc5ec\ub7ec \uc4f0\uae30\ub85c \ubd80\ud130\uc758 \ub370\uc774\ud130\ub77c\uace0 \ud560\uc9c0\ub77c\ub3c4<\/SPAN> <\/SPAN> \uc77d\uae30 \ud638\ucd9c\uc740 \uac00\ub2a5\ud55c \ub9ce\uc740 \ub370\uc774\ud130\ub97c<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ub9ac\ud134\ud560 \uac83\uc774\ub2e4.

PIPE_BUF\uc758 \uac12\uc740 Posix\uc5d0 \uc758\ud574\uc11c \uc801\uc5b4\ub3c4<\/SPAN> <\/SPAN> 512\ub294 \ub418\ub3c4\ub85d \ubcf4\uc7a5\ub41c\ub2e4. \uc774\uac74<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc5d0 \uc815\uc758\ub418\uc5b4
\uc788\uc744 \uac83\uc774\ub2e4. \uadf8\ub7ec\ub098 pathconf()\ud568\uc218\ub098 fpathconf()\ud568\uc218\uc5d0 \uc758\ud574 \uc790\ub3d9\uc73c\ub85c \uc9c8\uc758 \ub41c\ub2e4.

2.10.6 \uc5b4\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c\uc758 named pipe\uc0ac\uc6a9
----------------------------------------

<\/SPAN>    <\/SPAN><\/FONT><\/FONT>\uc11c\ubc84\uc640 \uba87\uba87 \ud074\ub77c\uc774\uc5b8\ud2b8\uac04\uc758 2-way \ud1b5\uc2e0\uc744 \uc5b4\ub5bb\uac8c \uad6c\ud604\ud558\ub294\uac00?

\ud55c \ubc88\uc5d0 \ud558\ub098 \uc774\uc0c1\uc758 \ud074\ub77c\uc774\uc5b8\ud2b8\uac00 \uc11c\ubc84\uc640<\/SPAN> <\/SPAN><\/FONT><\/FONT> \ud1b5\uc2e0\ud558\ub294\uac8c \uac00\ub2a5\ud558\ub2e4. PIPE_BUF \ubcf4\ub2e4 \ud074\ub77c\uc774\uc5b8\ud2b8\uac00 \ubcf4\ub0b4\ub294 \ub370\uc774\ud130\uac00 \uc791\uc740 \ud55c\uc740 \uac19\uc740 pipe\ub97c \ud1b5\ud574 \ud074\uc544\uc774\uc5b8\ud2b8 \ub4e4\uc774 \uc11c\ubc84\uc640 \ud1b5\uc2e0\ud560 \uc218 \uc788\ub2e4. \ubaa8\ub4e0 \ud074\ub77c\uc774\uc5b8\ud2b8\ub4e4\uc740 \uc11c\ubc84\uc758 incoming fifo\uc758 \uc774\ub984\uc744 \uc27d\uac8c \uc54c \uc218\uac00 \uc788\ub2e4.

\uadf8\ub7ec\ub098, \ud558\ub098\uc758 \ud30c\uc774\ud504\ub97c \uac00\uc9c0\uace0 \uadf8 \ud074\ub77c\uc774\uc5b8\ud2b8\ub4e4\uacfc \ud1b5\uc2e0\ud560 \uc218\ub294 \uc5c6\ub2e4. \ub9cc\uc57d<\/SPAN> <\/SPAN> \ud558\ub098 \uc774\uc0c1\uc758 \ud074\ub77c\uc774\uc5b8\ud2b8\ub4e4\uc774 \uac19\uc740 pipe\ub97c \ud1b5\ud574 \uc77d\uae30\ub97c \uc218\ud589\ud55c\ub2e4\uba74, \uc62c\ubc14\ub978 \ud074\ub77c\uc774\uc5b8\ud2b8\uac00 \uc801\ub2f9\ud55c \uc8fc\uc800\uc9c4 \ub370\uc774\ud130\ub97c<\/SPAN> <\/SPAN><\/FONT><\/FONT> \uc77d\uac8c \ub41c\ub2e4\ub294 \ubcf4\uc99d\uc744 \ud560 \uc218 \uc5c6\uae30 \ub54c\ubb38\uc774\ub2e4.

\uc194\ub8e8\uc158\uc740 \ud074\ub77c\uc774\uc5b8\ud2b8\uac00 \uc11c\ubc84\uc5d0 \ub370\uc774\ud130\ub97c \ubcf4\ub0b4\uae30 \uc804\uc5d0 \uc790\uc2e0\ub4e4\uc758 incoming pipe\ub97c \ub9cc\ub4e4\uac70\ub098 \ud074\ub77c\uc774\uc5b8\ud2b8\ub85c\ubd80\ud130 \ub370\uc774\ud130\ub97c \ubc1b\uc740 \ud6c4\uc5d0 \uc11c\ubc84\uc758 out going pipe\ub97c \ub9cc\ub4dc\ub294 \uac83\uc774\ub2e4.

\ud074\ub77c\uc774\uc5b8\ud2b8\uc758 PID\ub97c \uc0ac\uc6a9\ud558\uc5ec pipe\uc758 \uc774\ub984\uc744 \uc0ac\uc6a9\ud558\ub294 \uac83\uc774 \uc77c\ubc18\uc801\uc778 \ubc29\ubc95\uc774\ub2e4. \uc774\ub807\uac8c \ud568\uc73c\ub85c\uc368 \uc11c\ubc84\ub294 \ud074\ub77c\uc774\uc5b8\ud2b8\uc5d0\uac8c \uc62c\ubc14\ub978 \ub370\uc774\ud130\ub97c \uc8fc\ub294 \uac83\uc744 \ubcf4\uc7a5 \ud560 \uc218 \uc788\ub2e4 <\/FONT><\/SPAN><\/P>\n","protected":false},"excerpt":{"rendered":"

unix select \uc640 poll   2. \ud30c\uc77c \ud578\ub4e4\ub9c1 \uc77c\ubc18 (\ud30c\uc774\ud504\uc640 \uc18c\ucf13 \ud3ec\ud568)  2.1 \ub2e4\uc911 \uc5f0\uacb0(multiple connection)\uad00\ub9ac\ub294 \uc5b4\ub5bb\uac8c \ud558\ub294\uac00?    2.1.1 select()\ub294 \uc5b4\ub5bb\uac8c \uc0ac\uc6a9\ud558\ub294\uac00?    2.1.2 poll()\uc740 \uc5b4\ub5bb\uac8c \uc0ac\uc6a9\ud558\ub294\uac00?    2.1.3 select\ub098 poll\ucc98\ub7fc \ub3d9\uc2dc\uc5d0 SysV IPC\ub97c \uc0ac\uc6a9\ud560 \uc218 \uc788\ub294\uac00?  2.2 \ubc18\ub300\ucabd \uc5f0\uacb0\uc774 \ub04a\uacbc\ub294\uc9c0 \uc54c\uc218 \uc788\uc2b5\ub2c8\uae4c?  2.3 \ub514\ub809\ud1a0\ub9ac\ub97c \uc77d\ub294 \uac00\uc7a5 \uc88b\uc740 \ubc29\ubc95\uc740?  2.4 \uc5b4\ub5a4 \ub2e4\ub978 \uc0ac\ub78c\uc774 \ud30c\uc77c\uc744 […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center 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