1<fcntl.h>(P) POSIX Programmer's Manual <fcntl.h>(P)
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6 fcntl.h - file control options
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9 #include <fcntl.h>
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12 The <fcntl.h> header shall define the following requests and arguments
13 for use by the functions fcntl() and open().
14 Values for cmd used by fcntl() (the following values are unique) are as
16 follows:
17 F_DUPFD
19 Duplicate file descriptor.
20 F_GETFD
22 Get file descriptor flags.
23 F_SETFD
25 Set file descriptor flags.
26 F_GETFL
28 Get file status flags and file access modes.
29 F_SETFL
31 Set file status flags.
32 F_GETLK
34 Get record locking information.
35 F_SETLK
37 Set record locking information.
38 F_SETLKW
40 Set record locking information; wait if blocked.
41 F_GETOWN
43 Get process or process group ID to receive SIGURG signals.
44 F_SETOWN
46 Set process or process group ID to receive SIGURG signals.
47 File descriptor flags used for fcntl() are as follows:
50 FD_CLOEXEC
52 Close the file descriptor upon execution of an exec family func‐
53 tion.
54 Values for l_type used for record locking with fcntl() (the following
57 values are unique) are as follows:
58 F_RDLCK
60 Shared or read lock.
61 F_UNLCK
63 Unlock.
64 F_WRLCK
66 Exclusive or write lock.
67 The values used for l_whence, SEEK_SET, SEEK_CUR, and SEEK_END shall be
70 defined as described in <unistd.h> .
71 The following values are file creation flags and are used in the oflag
73 value to open(). They shall be bitwise-distinct.
74 O_CREAT
76 Create file if it does not exist.
77 O_EXCL Exclusive use flag.
79 O_NOCTTY
81 Do not assign controlling terminal.
82 O_TRUNC
84 Truncate flag.
85 File status flags used for open() and fcntl() are as follows:
88 O_APPEND
90 Set append mode.
91 O_DSYNC
93 Write according to synchronized I/O data integrity completion.
94 O_NONBLOCK
96 Non-blocking mode.
97 O_RSYNC
99 Synchronized read I/O operations.
100 O_SYNC Write according to synchronized I/O file integrity completion.
102 Mask for use with file access modes is as follows:
105 O_ACCMODE
107 Mask for file access modes.
108 File access modes used for open() and fcntl() are as follows:
111 O_RDONLY
113 Open for reading only.
114 O_RDWR Open for reading and writing.
116 O_WRONLY
118 Open for writing only.
119 The symbolic names for file modes for use as values of mode_t shall be
122 defined as described in <sys/stat.h> .
123 Values for advice used by posix_fadvise() are as follows:
125 POSIX_FADV_NORMAL
127 The application has no advice to give on its behavior with
129 respect to the specified data. It is the default characteristic
130 if no advice is given for an open file.
131 POSIX_FADV_SEQUENTIAL
133 The application expects to access the specified data sequen‐
135 tially from lower offsets to higher offsets.
136 POSIX_FADV_RANDOM
138 The application expects to access the specified data in a random
140 order.
141 POSIX_FADV_WILLNEED
143 The application expects to access the specified data in the near
145 future.
146 POSIX_FADV_DONTNEED
148 The application expects that it will not access the specified
150 data in the near future.
151 POSIX_FADV_NOREUSE
153 The application expects to access the specified data once and
155 then not reuse it thereafter.
156 The structure flock describes a file lock. It shall include the follow‐
159 ing members:
160 short l_type Type of lock; F_RDLCK, F_WRLCK, F_UNLCK.
163 short l_whence Flag for starting offset.
164 off_t l_start Relative offset in bytes.
165 off_t l_len Size; if 0 then until EOF.
166 pid_t l_pid Process ID of the process holding the lock; returned with F_GETLK.
167 The mode_t, off_t, and pid_t types shall be defined as described in
169 <sys/types.h> .
170 The following shall be declared as functions and may also be defined as
172 macros. Function prototypes shall be provided.
173 int creat(const char *, mode_t);
176 int fcntl(int, int, ...);
177 int open(const char *, int, ...);
178 int posix_fadvise(int, off_t, size_t, int);
180 int posix_fallocate(int, off_t, size_t);
181 Inclusion of the <fcntl.h> header may also make visible all symbols
184 from <sys/stat.h> and <unistd.h>.
185 The following sections are informative.
187
189 None.
190
192 None.
193
195 None.
196
198 <sys/stat.h> , <sys/types.h> , <unistd.h> , the System Interfaces vol‐
199 ume of IEEE Std 1003.1-2001, creat(), exec, fcntl(), open(), posix_fad‐
200 vise(), posix_fallocate(), posix_madvise()
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203 Portions of this text are reprinted and reproduced in electronic form
204 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
205 -- Portable Operating System Interface (POSIX), The Open Group Base
206 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
207 Electrical and Electronics Engineers, Inc and The Open Group. In the
208 event of any discrepancy between this version and the original IEEE and
209 The Open Group Standard, the original IEEE and The Open Group Standard
210 is the referee document. The original Standard can be obtained online
211 at http://www.opengroup.org/unix/online.html .
212IEEE/The Open Group 2003 <fcntl.h>(P)