fcntl.h.html
来自「unix 下的C开发手册,还用详细的例程。」· HTML 代码 · 共 228 行
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title><fcntl.h></title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_000_004_146"> </a>NAME</h4><blockquote>fcntl.h - file control options</blockquote><h4><a name = "tag_000_004_147"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <fcntl.h></code></pre></blockquote><h4><a name = "tag_000_004_148"> </a>DESCRIPTION</h4><blockquote>The<i><fcntl.h></i>header defines the following requests and arguments for use by the functions<i><a href="fcntl.html">fcntl()</a></i>and<i><a href="open.html">open()</a></i>.<p>Values for<i>cmd</i>used by<i><a href="fcntl.html">fcntl()</a></i>(the following values are unique):<dl compact><dt>F_DUPFD<dd>Duplicate file descriptor.<dt>F_GETFD<dd>Get file descriptor flags.<dt>F_SETFD<dd>Set file descriptor flags.<dt>F_GETFL<dd>Get file status flags and file access modes.<dt>F_SETFL<dd>Set file status flags.<dt>F_GETLK<dd>Get record locking information.<dt>F_SETLK<dd>Set record locking information.<dt>F_SETLKW<dd>Set record locking information; wait if blocked.</dl><p>File descriptor flags used for<i>fcntl</i>():<dl compact><dt>FD_CLOEXEC<dd>Close the file descriptor upon execution of an<i>exec</i>family function.</dl><p>Values for<i>l_type</i>used for record locking with<i>fcntl</i>()(the following values are unique):<dl compact><dt>F_RDLCK<dd>Shared or read lock.<dt>F_UNLCK<dd>Unlock.<dt>F_WRLCK<dd>Exclusive or write lock.</dl><p>The values used for<i>l_whence</i>,SEEK_SET, SEEK_CUR and SEEK_ENDare defined as described in<i><a href="unistd.h.html"><unistd.h></a></i>.<p>The following four sets of values for<i>oflag</i>used by<i>open</i>()are bitwise distinct:<dl compact><dt>O_CREAT<dd>Create file if it does not exist.<dt>O_EXCL<dd>Exclusive use flag.<dt>O_NOCTTY<dd>Do not assign controlling terminal.<dt>O_TRUNC<dd>Truncate flag.</dl><p>File status flags used for<i>open</i>()and<i>fcntl</i>():<dl compact><dt>O_APPEND<dd>Set append mode.<dt>O_DSYNC<dd>Write according to synchronised I/O data integrity completion.<dt>O_NONBLOCK<dd>Non-blocking mode.<dt>O_RSYNC<dd>Synchronised read I/O operations.<dt>O_SYNC<dd>Write according to synchronised I/O file integrity completion.</dl><p>Mask for use with file access modes:<dl compact><dt>O_ACCMODE<dd>Mask for file access modes.</dl><p>File access modes used for<i>open</i>()and<i>fcntl</i>():<dl compact><dt>O_RDONLY<dd>Open for reading only.<dt>O_RDWR<dd>Open for reading and writing.<dt>O_WRONLY<dd>Open for writing only.</dl><p>The symbolic names for file modes for use as values of<b>mode_t</b>are defined as described in<i><a href="sysstat.h.html"><sys/stat.h></a></i>.<p>The structure <b>flock</b> describes a file lock.It includes the following members:<pre><code>short l_type type of lock; F_RDLCK, F_WRLCK, F_UNLCKshort l_whence flag for starting offsetoff_t l_start relative offset in bytesoff_t l_len size; if 0 then until EOFpid_t l_pid process ID of the process holding the lock; returned with F_GETLK</code></pre><p>The<b>off_t</b>and<b>pid_t</b>types are defined as described in<i><a href="systypes.h.html"><sys/types.h></a></i>.<p>The following are declared as functions and may also be definedas macros.Function prototypes must be provided for use with an ISO Ccompiler.<pre><code>int <a href="creat.html">creat</a>(const char *, mode_t);int <a href="fcntl.html">fcntl</a>(int, int, ...);int <a href="open.html">open</a>(const char *, int, ...);</code></pre><p>Inclusion of the<i><fcntl.h></i>header may also make visible all symbols from<i><a href="sysstat.h.html"><sys/stat.h></a></i>and<i><a href="unistd.h.html"><unistd.h></a></i>.</blockquote><h4><a name = "tag_000_004_149"> </a>APPLICATION USAGE</h4><blockquote>None.</blockquote><h4><a name = "tag_000_004_150"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_004_151"> </a>SEE ALSO</h4><blockquote><i><a href="creat.html">creat()</a></i>,<i><a href="exec.html">exec</a></i>,<i><a href="fcntl.html">fcntl()</a></i>,<i><a href="open.html">open()</a></i>,<i><a href="sysstat.h.html"><sys/stat.h></a></i>,<i><a href="systypes.h.html"><sys/types.h></a></i>,<i><a href="unistd.h.html"><unistd.h></a></i>.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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