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Diffstat (limited to 'man2/pread.2')
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diff --git a/man2/pread.2 b/man2/pread.2 new file mode 100644 index 000000000..d0dffa921 --- /dev/null +++ b/man2/pread.2 @@ -0,0 +1,87 @@ +.\" Copyright (C) 1999 Joseph Samuel Myers. +.\" +.\" Permission is granted to make and distribute verbatim copies of this +.\" manual provided the copyright notice and this permission notice are +.\" preserved on all copies. +.\" +.\" Permission is granted to copy and distribute modified versions of this +.\" manual under the conditions for verbatim copying, provided that the +.\" entire resulting derived work is distributed under the terms of a +.\" permission notice identical to this one. +.\" +.\" Since the Linux kernel and libraries are constantly changing, this +.\" manual page may be incorrect or out-of-date. The author(s) assume no +.\" responsibility for errors or omissions, or for damages resulting from +.\" the use of the information contained herein. The author(s) may not +.\" have taken the same level of care in the production of this manual, +.\" which is licensed free of charge, as they might when working +.\" professionally. +.\" +.\" Formatted or processed versions of this manual, if unaccompanied by +.\" the source, must acknowledge the copyright and authors of this work. +.\" +.TH PREAD 2 1999-01-21 "Linux 2.2.0-pre9" "Linux Programmer's Manual" +.SH NAME +pread, pwrite \- read from or write to a file descriptor at a given offset +.SH SYNOPSIS +.B #define _XOPEN_SOURCE 500 +.sp +.B #include <unistd.h> +.sp +.BI "ssize_t pread(int " fd ", void *" buf ", size_t " count ", off_t " offset ); +.sp +.BI "ssize_t pwrite(int " fd ", const void *" buf ", size_t " count ", off_t " offset ); +.fi +.SH DESCRIPTION +.B pread() +reads up to +.I count +bytes from file descriptor +.I fd +at offset +.I offset +(from the start of the file) into the buffer starting at +.IR buf . +The file offset is not changed. +.PP +.B pwrite() +writes up to +.I count +bytes from the buffer starting at +.I buf +to the file descriptor +.I fd +at offset +.IR offset . +The file offset is not changed. +.PP +The file referenced by +.I fd +must be capable of seeking. +.SH "RETURN VALUE" +On success, the number of bytes read or written is returned (zero +indicates that nothing was written, in the case of \fBpwrite\fR, or +end of file, in the case of \fBpread\fR), or \-1 on error, in which +case +.I errno +is set to indicate the error. +.SH ERRORS +.B pread +can fail and set +.I errno +to any error specified for \fBread\fR(2) or \fBlseek\fR(2). +.B pwrite +can fail and set +.I errno +to any error specified for \fBwrite\fR(2) or \fBlseek\fR(2). +.SH "CONFORMING TO" +Unix98 +.SH HISTORY +The \fBpread\fR and \fBpwrite\fR system calls were added to Linux in +version 2.1.60; the entries in the i386 system call table were added +in 2.1.69. The libc support (including emulation on older kernels +without the system calls) was added in glibc 2.1. +.SH "SEE ALSO" +.BR lseek (2), +.BR read (2), +.BR write (2) |