man0p/fcntl.h.0p

   1 .\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
   2 .TH "<fcntl.h>" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
   3 .\" <fcntl.h>
   4 .SH NAME
   5 fcntl.h \- file control options
   6 .SH SYNOPSIS
   7 .LP
   8 \fB#include <fcntl.h>\fP
   9 .SH DESCRIPTION
  10 .LP
  11 The \fI<fcntl.h>\fP header shall define the following requests and
  12 arguments for use by the functions \fIfcntl\fP() and \fIopen\fP().
  13 .LP
  14 Values for \fIcmd\fP used by \fIfcntl\fP() (the following values are
  15 unique) are as
  16 follows:
  17 .TP 7
  18 F_DUPFD
  19 Duplicate file descriptor.
  20 .TP 7
  21 F_GETFD
  22 Get file descriptor flags.
  23 .TP 7
  24 F_SETFD
  25 Set file descriptor flags.
  26 .TP 7
  27 F_GETFL
  28 Get file status flags and file access modes.
  29 .TP 7
  30 F_SETFL
  31 Set file status flags.
  32 .TP 7
  33 F_GETLK
  34 Get record locking information.
  35 .TP 7
  36 F_SETLK
  37 Set record locking information.
  38 .TP 7
  39 F_SETLKW
  40 Set record locking information; wait if blocked.
  41 .TP 7
  42 F_GETOWN
  43 Get process or process group ID to receive SIGURG signals.
  44 .TP 7
  45 F_SETOWN
  46 Set process or process group ID to receive SIGURG signals.
  47 .sp
  48 .LP
  49 File descriptor flags used for \fIfcntl\fP() are as follows:
  50 .TP 7
  51 FD_CLOEXEC
  52 Close the file descriptor upon execution of an \fIexec\fP family function.
  53 .sp
  54 .LP
  55 Values for \fIl_type\fP used for record locking with \fIfcntl\fP()
  56 (the following values
  57 are unique) are as follows:
  58 .TP 7
  59 F_RDLCK
  60 Shared or read lock.
  61 .TP 7
  62 F_UNLCK
  63 Unlock.
  64 .TP 7
  65 F_WRLCK
  66 Exclusive or write lock.
  67 .sp
  68 .LP
  69 The values used for \fIl_whence\fP, SEEK_SET, SEEK_CUR, and SEEK_END
  70 shall be defined as described in \fI<unistd.h>\fP .
  71 .LP
  72 The following values are file creation flags and are used in the \fIoflag\fP
  73 value to \fIopen\fP(). They shall be bitwise-distinct.
  74 .TP 7
  75 O_CREAT
  76 Create file if it does not exist.
  77 .TP 7
  78 O_EXCL
  79 Exclusive use flag.
  80 .TP 7
  81 O_NOCTTY
  82 Do not assign controlling terminal.
  83 .TP 7
  84 O_TRUNC
  85 Truncate flag.
  86 .sp
  87 .LP
  88 File status flags used for \fIopen\fP() and \fIfcntl\fP() are as follows:
  89 .TP 7
  90 O_APPEND
  91 Set append mode.
  92 .TP 7
  93 O_DSYNC
  94 Write according to synchronized I/O data integrity completion.
  95 .TP 7
  96 O_NONBLOCK
  97 Non-blocking mode.
  98 .TP 7
  99 O_RSYNC
 100 Synchronized read I/O operations.
 101 .TP 7
 102 O_SYNC
 103 Write according to synchronized I/O file integrity completion.
 104 .sp
 105 .LP
 106 Mask for use with file access modes is as follows:
 107 .TP 7
 108 O_ACCMODE
 109 Mask for file access modes.
 110 .sp
 111 .LP
 112 File access modes used for \fIopen\fP() and \fIfcntl\fP() are as follows:
 113 .TP 7
 114 O_RDONLY
 115 Open for reading only.
 116 .TP 7
 117 O_RDWR
 118 Open for reading and writing.
 119 .TP 7
 120 O_WRONLY
 121 Open for writing only.
 122 .sp
 123 .LP
 124 The symbolic names for file modes for use as values of \fBmode_t\fP
 125 shall be defined as described in \fI<sys/stat.h>\fP .
 126 .LP
 127 Values for \fIadvice\fP used by \fIposix_fadvise\fP() are as follows:
 128 .TP 7
 129 POSIX_FADV_NORMAL
 130 .sp
 131 The application has no advice to give on its behavior with respect
 132 to the specified data. It is the default characteristic if no
 133 advice is given for an open file.
 134 .TP 7
 135 POSIX_FADV_SEQUENTIAL
 136 .sp
 137 The application expects to access the specified data sequentially
 138 from lower offsets to higher offsets.
 139 .TP 7
 140 POSIX_FADV_RANDOM
 141 .sp
 142 The application expects to access the specified data in a random order.
 143 .TP 7
 144 POSIX_FADV_WILLNEED
 145 .sp
 146 The application expects to access the specified data in the near future.
 147 .TP 7
 148 POSIX_FADV_DONTNEED
 149 .sp
 150 The application expects that it will not access the specified data
 151 in the near future.
 152 .TP 7
 153 POSIX_FADV_NOREUSE
 154 .sp
 155 The application expects to access the specified data once and then
 156 not reuse it thereafter.
 157 .sp
 158 .LP
 159 The structure \fBflock\fP describes a file lock. It shall include
 160 the following members:
 161 .sp
 162 .RS
 163 .nf
 164
 165 \fBshort  l_type  \fP Type of lock; F_RDLCK, F_WRLCK, F_UNLCK. \fB
 166 short  l_whence\fP Flag for starting offset. \fB
 167 off_t  l_start \fP Relative offset in bytes. \fB
 168 off_t  l_len   \fP Size; if 0 then until EOF. \fB
 169 pid_t  l_pid   \fP Process ID of the process holding the lock; returned with F_GETLK. \fB
 170 \fP
 171 .fi
 172 .RE
 173 .LP
 174 The \fBmode_t\fP, \fBoff_t\fP, and \fBpid_t\fP types shall be defined
 175 as described in \fI<sys/types.h>\fP .
 176 .LP
 177 The following shall be declared as functions and may also be defined
 178 as macros. Function prototypes shall be provided.
 179 .sp
 180 .RS
 181 .nf
 182
 183 \fBint  creat(const char *, mode_t);
 184 int  fcntl(int, int, ...);
 185 int  open(const char *, int, ...);
 186
 187 int  posix_fadvise(int, off_t, size_t, int);
 188 int  posix_fallocate(int, off_t, size_t);
 189
 190 \fP
 191 .fi
 192 .RE
 193 .LP
 194 Inclusion of the \fI<fcntl.h>\fP header may also make visible all
 195 symbols from \fI<sys/stat.h>\fP and \fI<unistd.h>\fP.
 196 .LP
 197 \fIThe following sections are informative.\fP
 198 .SH APPLICATION USAGE
 199 .LP
 200 None.
 201 .SH RATIONALE
 202 .LP
 203 None.
 204 .SH FUTURE DIRECTIONS
 205 .LP
 206 None.
 207 .SH SEE ALSO
 208 .LP
 209 \fI<sys/stat.h>\fP , \fI<sys/types.h>\fP , \fI<unistd.h>\fP , the
 210 System Interfaces volume of IEEE\ Std\ 1003.1-2001, \fIcreat\fP(),
 211 \fIexec\fP, \fIfcntl\fP(), \fIopen\fP(), \fIposix_fadvise\fP(), \fIposix_fallocate\fP(),
 212 \fIposix_madvise\fP()
 213 .SH COPYRIGHT
 214 Portions of this text are reprinted and reproduced in electronic form
 215 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
 216 -- Portable Operating System Interface (POSIX), The Open Group Base
 217 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
 218 Electrical and Electronics Engineers, Inc and The Open Group. In the
 219 event of any discrepancy between this version and the original IEEE and
 220 The Open Group Standard, the original IEEE and The Open Group Standard
 221 is the referee document. The original Standard can be obtained online at
 222 http://www.opengroup.org/unix/online.html .