| 1 | .\"
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| 2 | .\" Copyright (c) 2000 Sheldon Hearn <sheldonh@FreeBSD.org>.
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| 3 | .\" All rights reserved.
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| 4 | .\"
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| 5 | .\" Redistribution and use in source and binary forms, with or without
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| 6 | .\" modification, are permitted provided that the following conditions
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| 7 | .\" are met:
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| 8 | .\" 1. Redistributions of source code must retain the above copyright
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| 9 | .\" notice, this list of conditions and the following disclaimer.
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| 10 | .\" 2. Redistributions in binary form must reproduce the above copyright
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| 11 | .\" notice, this list of conditions and the following disclaimer in the
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| 12 | .\" documentation and/or other materials provided with the distribution.
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| 13 | .\"
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| 14 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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| 15 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 16 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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| 17 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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| 18 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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| 19 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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| 20 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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| 21 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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| 22 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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| 23 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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| 24 | .\" SUCH DAMAGE.
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| 25 | .\"
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| 26 | .\" $FreeBSD: src/usr.bin/truncate/truncate.1,v 1.12 2005/01/17 07:44:32 ru Exp $
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| 27 | .\"
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| 28 | .Dd July 4, 2000
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| 29 | .Dt TRUNCATE 1
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| 30 | .Os
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| 31 | .SH NAME
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| 32 | truncate \- truncate or extend the length of files
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| 33 | .SH SYNOPSIS
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| 34 | truncate
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| 35 | .Op Fl c
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| 36 | .Bk -words
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| 37 | .Fl s Xo
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| 38 | .Sm off
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| 39 | .Op Cm + | -
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| 40 | .Ar size
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| 41 | .Op Cm K | k | M | m | G | g
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| 42 | .Sm on
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| 43 | .Xc
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| 44 | .Ek
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| 45 | .Ar
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| 46 | truncate
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| 47 | .Op Fl c
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| 48 | .Bk -words
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| 49 | .Fl r Ar rfile
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| 50 | .Ek
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| 51 | .Ar
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| 52 | .SH DESCRIPTION
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| 53 | The
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| 54 | truncate
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| 55 | utility adjusts the length of each regular file given on the command-line.
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| 56 | .Pp
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| 57 | The following options are available:
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| 58 | .Bl -tag -width indent
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| 59 | .It Fl c
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| 60 | Do not create files if they do not exist.
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| 61 | The
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| 62 | truncate
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| 63 | utility does not treat this as an error.
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| 64 | No error messages are displayed
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| 65 | and the exit value is not affected.
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| 66 | .It Fl r Ar rfile
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| 67 | Truncate files to the length of the file
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| 68 | .Ar rfile .
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| 69 | .It Fl s Xo
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| 70 | .Sm off
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| 71 | .Op Cm + | -
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| 72 | .Ar size
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| 73 | .Op Cm K | k | M | m | G | g
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| 74 | .Sm on
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| 75 | .Xc
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| 76 | If the
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| 77 | .Ar size
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| 78 | argument is preceded by a plus sign
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| 79 | .Pq Cm + ,
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| 80 | files will be extended by this number of bytes.
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| 81 | If the
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| 82 | .Ar size
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| 83 | argument is preceded by a dash
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| 84 | .Pq Cm - ,
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| 85 | file lengths will be reduced by no more than this number of bytes,
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| 86 | to a minimum length of zero bytes.
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| 87 | Otherwise, the
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| 88 | .Ar size
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| 89 | argument specifies an absolute length to which all files
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| 90 | should be extended or reduced as appropriate.
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| 91 | .Pp
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| 92 | The
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| 93 | .Ar size
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| 94 | argument may be suffixed with one of
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| 95 | .Cm K ,
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| 96 | .Cm M
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| 97 | or
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| 98 | .Cm G
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| 99 | (either upper or lower case) to indicate a multiple of
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| 100 | Kilobytes, Megabytes or Gigabytes
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| 101 | respectively.
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| 102 | .El
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| 103 | .Pp
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| 104 | Exactly one of the
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| 105 | .Fl r
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| 106 | and
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| 107 | .Fl s
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| 108 | options must be specified.
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| 109 | .Pp
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| 110 | If a file is made smaller, its extra data is lost.
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| 111 | If a file is made larger,
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| 112 | it will be extended as if by writing bytes with the value zero.
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| 113 | If the file does not exist,
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| 114 | it is created unless the
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| 115 | .Fl c
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| 116 | option is specified.
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| 117 | .Pp
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| 118 | Note that,
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| 119 | while truncating a file causes space on disk to be freed,
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| 120 | extending a file does not cause space to be allocated.
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| 121 | To extend a file and actually allocate the space,
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| 122 | it is necessary to explicitly write data to it,
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| 123 | using (for example) the shell's
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| 124 | .Ql >>
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| 125 | redirection syntax, or
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| 126 | .Xr dd 1 .
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| 127 | .SH EXIT STATUS
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| 128 | .Ex -std
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| 129 | If the operation fails for an argument,
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| 130 | truncate
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| 131 | will issue a diagnostic
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| 132 | and continue processing the remaining arguments.
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| 133 | .SH SEE ALSO
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| 134 | .BR dd(1),
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| 135 | .BR touch(1),
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| 136 | .BR truncate(2)
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| 137 | .SH STANDARDS
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| 138 | The
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| 139 | truncate
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| 140 | utility conforms to no known standards.
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| 141 | .SH HISTORY
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| 142 | The
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| 143 | truncate
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| 144 | utility first appeared in FreeBSD 4.2.
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| 145 | .SH AUTHORS
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| 146 | The truncate utility was written by Sheldon Hearn <sheldonh@starjuice.net>.
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