1.\" 2.\" Copyright (c) 2000 Sheldon Hearn <sheldonh@FreeBSD.org>. 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD: src/usr.bin/truncate/truncate.1,v 1.4.2.7 2001/08/16 13:17:08 ru Exp $ 27.\" $DragonFly: src/usr.bin/truncate/truncate.1,v 1.2 2003/06/17 04:29:33 dillon Exp $ 28.\" 29.Dd July 4, 2000 30.Dt TRUNCATE 1 31.Os 32.Sh NAME 33.Nm truncate 34.Nd truncate or extend the length of files 35.Sh SYNOPSIS 36.Nm 37.Op Fl c 38.Bk -words 39.Fl s Xo 40.Sm off 41.Op Cm + | - 42.Ar size 43.Op Cm K | M | G 44.Sm on 45.Xc 46.Ek 47.Ar 48.Nm 49.Op Fl c 50.Bk -words 51.Fl r Ar rfile 52.Ek 53.Ar 54.Sh DESCRIPTION 55The 56.Nm 57utility adjusts the length of each regular file given on the command-line. 58.Pp 59The following options are available: 60.Bl -tag -width indent 61.It Fl c 62Do not create files if they do not exist. 63The 64.Nm 65utility does not treat this as an error. 66No error messages are displayed 67and the exit value is not affected. 68.It Fl r Ar rfile 69Truncate files to the length of the file 70.Ar rfile . 71.It Fl s Xo 72.Sm off 73.Op Cm + | - 74.Ar size 75.Op Cm K | M | G 76.Sm on 77.Xc 78If the 79.Ar size 80argument is preceded by a plus sign 81.Pq Cm + , 82files will be extended by this number of bytes. 83If the 84.Ar size 85argument is preceded by a dash 86.Pq Cm - , 87file lengths will be reduced by no more than this number of bytes, 88to a minimum length of zero bytes. 89Otherwise, the 90.Ar size 91argument specifies an absolute length to which all files 92should be extended or reduced as appropriate. 93.Pp 94The 95.Ar size 96argument may be suffixed with one of 97.Cm K , 98.Cm M 99or 100.Cm G 101to indicate a multiple of 102Kilobytes, Megabytes or Gigabytes 103respectively. 104.El 105.Pp 106Exactly one of the 107.Fl r 108and 109.Fl s 110options must be specified. 111.Pp 112If a file is made smaller, its extra data is lost. 113If a file is made larger, 114it will be extended as if by writing bytes with the value zero. 115If the file does not exist, 116it is created unless the 117.Fl c 118option is specified. 119.Pp 120Note that, 121while truncating a file causes space on disk to be freed, 122extending a file does not cause space to be allocated. 123To extend a file and actually allocate the space, 124it is necessary to explicitly write data to it, 125using (for example) the shell's 126.Ql >> 127redirection syntax, or 128.Xr dd 1 . 129.Sh DIAGNOSTICS 130.Ex -std 131If the operation fails for an argument, 132.Nm 133will issue a diagnostic 134and continue processing the remaining arguments. 135.Sh SEE ALSO 136.Xr dd 1 , 137.Xr touch 1 , 138.Xr truncate 2 139.Sh STANDARDS 140The 141.Nm 142utility conforms to no known standards. 143.Sh HISTORY 144The 145.Nm 146utility first appeared in 147.Fx 4.2 . 148.Sh AUTHORS 149The 150.Nm 151utility was written by 152.An Sheldon Hearn 153.Aq sheldonh@starjuice.net . 154