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unistd(3) [netbsd man page]

UNISTD(3)						   BSD Library Functions Manual 						 UNISTD(3)

NAME
unistd -- standard symbolic constants and types SYNOPSIS
#include <unistd.h> DESCRIPTION
The <unistd.h> header forms the basis of the Portable Operating System Interface for Unix (POSIX) API. It includes definitions for numerous functions, symbolic constants, and types. Among these are: o The implementation-defined NULL pointer constant. o Types such as size_t, ssize_t, pid_t, and intptr_t. o Various limits and other symbolic constants described in pathconf(2) and sysconf(3). o Prototypes for several important system calls and library routines such as chown(2), dup(2), execl(3), fork(2), pipe(2), rmdir(2), setuid(2), and write(2). o The symbolic constant _POSIX_VERSION that defines the version of the POSIX standard to which the implementation conforms. o Various other _POSIX -prefixed symbolic constants that indicate whether the system implements some optional part of the standard. Examples include such constants as _POSIX_IPV6 for inet6(4) functionality and _POSIX_ASYNCHRONOUS_IO for aio(3). SEE ALSO
limits(3), stddef(3), stdint(3), stdlib(3), types(3) STANDARDS
The <unistd.h> header conforms to IEEE Std 1003.1-2001 (``POSIX.1''). BSD
August 9, 2011 BSD

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<sys/uio.h>(P)						     POSIX Programmer's Manual						    <sys/uio.h>(P)

NAME
sys/uio.h - definitions for vector I/O operations SYNOPSIS
#include <sys/uio.h> DESCRIPTION
The <sys/uio.h> header shall define the iovec structure that includes at least the following members: void *iov_base Base address of a memory region for input or output. size_t iov_len The size of the memory pointed to by iov_base. The <sys/uio.h> header uses the iovec structure for scatter/gather I/O. The ssize_t and size_t types shall be defined as described in <sys/types.h>. The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided. ssize_t readv(int, const struct iovec *, int); ssize_t writev(int, const struct iovec *, int); The following sections are informative. APPLICATION USAGE
The implementation can put a limit on the number of scatter/gather elements which can be processed in one call. The symbol {IOV_MAX} defined in <limits.h> should always be used to learn about the limits instead of assuming a fixed value. RATIONALE
Traditionally, the maximum number of scatter/gather elements the system can process in one call were described by the symbolic value {UIO_MAXIOV}. In IEEE Std 1003.1-2001 this value is replaced by the constant {IOV_MAX} which can be found in <limits.h>. FUTURE DIRECTIONS
None. SEE ALSO
<limits.h> , <sys/types.h> , the System Interfaces volume of IEEE Std 1003.1-2001, read(), write() COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol- ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html . IEEE
/The Open Group 2003 <sys/uio.h>(P)

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