1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Chris Torek. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.Dd July 1, 2026 32.Dt BCOPY 9 33.Os 34.Sh NAME 35.Nm bcopy 36.Nd copy bytes in object 37.Sh SYNOPSIS 38.In sys/systm.h 39.Ft void 40.Fn bcopy "const void *src" "void *dst" "size_t len" 41.Sh DESCRIPTION 42The 43.Fn bcopy 44function copies 45.Fa len 46bytes from object 47.Fa src 48to object 49.Fa dst 50preserving the provenance of pointers in the copied object 51.Pq see Xr memory_model 7 for further information . 52The two objects may overlap. 53If 54.Fa len 55is zero, no bytes are copied. 56.Pp 57The 58.Fn bcopy 59function is deprecated and 60.Fn memcpy 61or 62.Fn memmove 63should be used as appropriate in new code. 64.Sh SEE ALSO 65.Xr memcpy 9 , 66.Xr memmove 9 67.Sh HISTORY 68A 69.Fn bcopy 70function appeared in 71.Bx 4.2 . 72.Pp 73.St -p1003.1-2008 74removes the specification of 75.Fn bcopy 76and it is marked as LEGACY in 77.St -p1003.1-2004 . 78New programs should use 79.Xr memmove 3 . 80If the input and output buffer do not overlap, then 81.Xr memcpy 3 82is more efficient. 83Note that 84.Fn bcopy 85takes 86.Ar src 87and 88.Ar dst 89in the opposite order from 90.Fn memmove 91and 92.Fn memcpy . 93In practice, 94.In sys/systm.h 95defines 96.Fn bcopy 97as a macro that calls 98.Fn memmove 99since 100.Fx 12.0 . 101