1.\" 2.\" Copyright (c) 2000 Sheldon Hearn <sheldonh@FreeBSD.org>. 3.\" All rights reserved. 4.\" Copyright (c) 2021 The FreeBSD Foundation 5.\" 6.\" Portions of this manual page were written by Ka Ho Ng <khng@FreeBSD.org> 7.\" under sponsorship from the FreeBSD Foundation. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.Dd August 19, 2021 31.Dt TRUNCATE 1 32.Os 33.Sh NAME 34.Nm truncate 35.Nd truncate, extend the length of files, or perform space management in files 36.Sh SYNOPSIS 37.Nm 38.Op Fl c 39.Bk -words 40.Fl s Xo 41.Sm off 42.Op Cm + | - | % | / 43.Ar size 44.Op Cm SUFFIX 45.Sm on 46.Xc 47.Ek 48.Ar 49.Nm 50.Op Fl c 51.Bk -words 52.Fl r Ar rfile 53.Ek 54.Ar 55.Nm 56.Op Fl c 57.Bk -words 58.Fl d 59.Oo 60.Fl o Xo 61.Sm off 62.Ar offset 63.Op Cm SUFFIX 64.Sm on 65.Xc 66.Oc 67.Fl l Xo 68.Sm off 69.Ar length 70.Op Cm SUFFIX 71.Sm on 72.Xc 73.Ek 74.Ar 75.Sh DESCRIPTION 76The 77.Nm 78utility adjusts the length of each regular file given on the command-line, or 79performs space management with the given offset and the length over a regular 80file given on the command-line. 81.Pp 82The following options are available: 83.Bl -tag -width indent 84.It Fl c 85Do not create files if they do not exist. 86The 87.Nm 88utility does not treat this as an error. 89No error messages are displayed 90and the exit value is not affected. 91.It Fl r Ar rfile 92Truncate or extend files to the length of the file 93.Ar rfile . 94.It Fl s Xo 95.Sm off 96.Op Cm + | - | % | / 97.Ar size 98.Op Cm SUFFIX 99.Sm on 100.Xc 101If the 102.Ar size 103argument is preceded by a plus sign 104.Pq Cm + , 105files will be extended by this number of bytes. 106If the 107.Ar size 108argument is preceded by a dash 109.Pq Cm - , 110file lengths will be reduced by no more than this number of bytes, 111to a minimum length of zero bytes. 112If the 113.Ar size 114argument is preceded by a percent sign 115.Pq Cm % , 116files will be round up to a multiple of this number of bytes. 117If the 118.Ar size 119argument is preceded by a slash sign 120.Pq Cm / , 121files will be round down to a multiple of this number of bytes, 122to a minimum length of zero bytes. 123Otherwise, the 124.Ar size 125argument specifies an absolute length to which all files 126should be extended or reduced as appropriate. 127.It Fl d 128Zero a region in the specified file. 129If the underlying file system of the given file supports hole-punching, 130file system space deallocation may be performed in the operation region. 131.It Fl o Ar offset 132The space management operation is performed at the given 133.Ar offset 134bytes in the file. 135If this option is not specified, the operation is performed at the beginning of the file. 136.It Fl l Ar length 137The length of the operation range in bytes. 138This option must always be specified if option 139.Fl d 140is specified, and must be greater than 0. 141.El 142.Pp 143The 144.Ar size , 145.Ar offset 146and 147.Ar length 148arguments may be suffixed with one of 149.Cm K , 150.Cm M , 151.Cm G 152or 153.Cm T 154(either upper or lower case) to indicate a multiple of 155Kilobytes, Megabytes, Gigabytes or Terabytes 156respectively. 157.Pp 158Exactly one of the 159.Fl r , 160.Fl s 161and 162.Fl d 163options must be specified. 164.Pp 165If a file is made smaller, its extra data is lost. 166If a file is made larger, 167it will be extended as if by writing bytes with the value zero. 168If the file does not exist, 169it is created unless the 170.Fl c 171option is specified. 172.Pp 173Note that, 174while truncating a file causes space on disk to be freed, 175extending a file does not cause space to be allocated. 176To extend a file and actually allocate the space, 177it is necessary to explicitly write data to it, 178using (for example) the shell's 179.Ql >> 180redirection syntax, or 181.Xr dd 1 . 182.Sh EXIT STATUS 183.Ex -std 184If the operation fails for an argument, 185.Nm 186will issue a diagnostic 187and continue processing the remaining arguments. 188.Sh EXAMPLES 189Adjust the size of the file 190.Pa test_file 191to 10 Megabytes but do not create it if it does not exist: 192.Bd -literal -offset indent 193truncate -c -s +10M test_file 194.Ed 195.Pp 196Same as above but create the file if it does not exist: 197.Bd -literal -offset indent 198truncate -s +10M test_file 199ls -l test_file 200-rw-r--r-- 1 root wheel 10485760 Jul 22 18:48 test_file 201.Ed 202.Pp 203Adjust the size of 204.Pa test_file 205to the size of the kernel and create another file 206.Pa test_file2 207with the same size: 208.Bd -literal -offset indent 209truncate -r /boot/kernel/kernel test_file test_file2 210ls -l /boot/kernel/kernel test_file* 211-r-xr-xr-x 1 root wheel 31352552 May 15 14:18 /boot/kernel/kernel* 212-rw-r--r-- 1 root wheel 31352552 Jul 22 19:15 test_file 213-rw-r--r-- 1 root wheel 31352552 Jul 22 19:15 test_file2 214.Ed 215.Pp 216Downsize 217.Pa test_file 218in 5 Megabytes: 219.Bd -literal -offset indent 220# truncate -s -5M test_file 221ls -l test_file* 222-rw-r--r-- 1 root wheel 26109672 Jul 22 19:17 test_file 223-rw-r--r-- 1 root wheel 31352552 Jul 22 19:15 test_file2 224.Ed 225.Sh SEE ALSO 226.Xr dd 1 , 227.Xr touch 1 , 228.Xr fspacectl 2 , 229.Xr truncate 2 230.Sh STANDARDS 231The 232.Nm 233utility conforms to no known standards. 234.Sh HISTORY 235The 236.Nm 237utility first appeared in 238.Fx 4.2 . 239.Sh AUTHORS 240The 241.Nm 242utility was written by 243.An Sheldon Hearn Aq Mt sheldonh@starjuice.net . 244Hole-punching support of this 245utility was developed by 246.An Ka Ho Ng Aq Mt khng@FreeBSD.org . 247