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 1.12 2005/01/17 07:44:32 ru Exp $ 27.\" 28.Dd July 4, 2000 29.Dt TRUNCATE 1 30.Os 31.Sh NAME 32truncate \- truncate or extend the length of files 33.Sh SYNOPSIS 34truncate 35.Op Fl c 36.Bk -words 37.Fl s Xo 38.Sm off 39.Op Cm + | - 40.Ar size 41.Op Cm K | k | M | m | G | g 42.Sm on 43.Xc 44.Ek 45.Ar 46truncate 47.Op Fl c 48.Bk -words 49.Fl r Ar rfile 50.Ek 51.Ar 52.Sh DESCRIPTION 53The 54truncate 55utility adjusts the length of each regular file given on the command-line. 56.Pp 57The following options are available: 58.Bl -tag -width indent 59.It Fl c 60Do not create files if they do not exist. 61The 62truncate 63utility does not treat this as an error. 64No error messages are displayed 65and the exit value is not affected. 66.It Fl r Ar rfile 67Truncate files to the length of the file 68.Ar rfile . 69.It Fl s Xo 70.Sm off 71.Op Cm + | - 72.Ar size 73.Op Cm K | k | M | m | G | g 74.Sm on 75.Xc 76If the 77.Ar size 78argument is preceded by a plus sign 79.Pq Cm + , 80files will be extended by this number of bytes. 81If the 82.Ar size 83argument is preceded by a dash 84.Pq Cm - , 85file lengths will be reduced by no more than this number of bytes, 86to a minimum length of zero bytes. 87Otherwise, the 88.Ar size 89argument specifies an absolute length to which all files 90should be extended or reduced as appropriate. 91.Pp 92The 93.Ar size 94argument may be suffixed with one of 95.Cm K , 96.Cm M 97or 98.Cm G 99(either upper or lower case) to indicate a multiple of 100Kilobytes, Megabytes or Gigabytes 101respectively. 102.El 103.Pp 104Exactly one of the 105.Fl r 106and 107.Fl s 108options must be specified. 109.Pp 110If a file is made smaller, its extra data is lost. 111If a file is made larger, 112it will be extended as if by writing bytes with the value zero. 113If the file does not exist, 114it is created unless the 115.Fl c 116option is specified. 117.Pp 118Note that, 119while truncating a file causes space on disk to be freed, 120extending a file does not cause space to be allocated. 121To extend a file and actually allocate the space, 122it is necessary to explicitly write data to it, 123using (for example) the shell's 124.Ql >> 125redirection syntax, or 126.Xr dd 1 . 127.Sh EXIT STATUS 128.Ex -std 129If the operation fails for an argument, 130truncate 131will issue a diagnostic 132and continue processing the remaining arguments. 133.Sh SEE ALSO 134.Xr dd 1 , 135.Xr touch 1 , 136.Xr truncate 2 137.Sh STANDARDS 138The 139truncate 140utility conforms to no known standards. 141.Sh HISTORY 142The 143truncate 144utility first appeared in FreeBSD 4.2. 145.Sh AUTHORS 146The truncate utility was written by Sheldon Hearn <sheldonh@starjuice.net>. 147