155 lines
3.7 KiB
Groff
155 lines
3.7 KiB
Groff
.\"
|
|
.\" Copyright (c) 2000 Sheldon Hearn <sheldonh@FreeBSD.org>.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd July 4, 2000
|
|
.Dt TRUNCATE 1
|
|
.Os
|
|
.Sh NAME
|
|
.Nm truncate
|
|
.Nd truncate or extend the length of files
|
|
.Sh SYNOPSIS
|
|
.Nm
|
|
.Op Fl c
|
|
.Bk -words
|
|
.Fl s Xo
|
|
.Sm off
|
|
.Op + | -
|
|
.Ar size
|
|
.Op K | M | G
|
|
.Sm on
|
|
.Xc
|
|
.Ek
|
|
.Ar
|
|
.Nm
|
|
.Op Fl c
|
|
.Bk -words
|
|
.Fl r Ar rfile
|
|
.Ek
|
|
.Ar
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
utility adjusts the length of each regular file given on the command-line.
|
|
.Pp
|
|
The following options are available:
|
|
.Bl -tag -width indent
|
|
.It Fl c
|
|
Do not create files if they do not exist.
|
|
The
|
|
.Nm
|
|
utility does not treat this as an error.
|
|
No error messages are displayed
|
|
and the exit value is not affected.
|
|
.It Fl r Ar rfile
|
|
Truncate files to the length of the file
|
|
.Ar rfile .
|
|
.It Fl s Xo
|
|
.Sm off
|
|
.Op + | -
|
|
.Ar size
|
|
.Op K | M | G
|
|
.Sm on
|
|
.Xc
|
|
If the
|
|
.Ar size
|
|
argument is preceded by a plus sign
|
|
.Pq Sq + ,
|
|
files will be extended by this number of bytes.
|
|
If the
|
|
.Ar size
|
|
argument is preceded by a dash
|
|
.Pq Sq - ,
|
|
file lengths will be reduced by no more than this number of bytes,
|
|
to a minimum length of zero bytes.
|
|
Otherwise, the
|
|
.Ar size
|
|
argument specifies an absolute length to which all files
|
|
should be extended or reduced as appropriate.
|
|
.Pp
|
|
The
|
|
.Ar size
|
|
argument may be suffixed with one of
|
|
.Sq K ,
|
|
.Sq M ,
|
|
.Sq G
|
|
to indicate a multiple of
|
|
Kilobytes, Megabytes or Gigabytes
|
|
respectively.
|
|
.El
|
|
.Pp
|
|
Exactly one of the
|
|
.Fl r
|
|
and
|
|
.Fl s
|
|
options must be specified.
|
|
.Pp
|
|
If a file is made smaller, its extra data is lost.
|
|
If a file is made larger,
|
|
it will be extended as if by writing bytes with the value zero.
|
|
If the file does not exist,
|
|
it is created unless the
|
|
.Fl c
|
|
option is specified.
|
|
.Pp
|
|
Note that,
|
|
while truncating a file causes space on disk to be freed,
|
|
extending a file does not cause space to be allocated.
|
|
To extend a file and actually allocate the space,
|
|
it is necessary to explicitly write data to it,
|
|
using (for example) the shell's
|
|
.Ql >>
|
|
redirection syntax, or
|
|
.Xr dd 1 .
|
|
.Sh DIAGNOSTICS
|
|
The
|
|
.Nm
|
|
utility exits 0 on success,
|
|
and >0 if an error occurs.
|
|
If the operation fails for an argument,
|
|
.Nm
|
|
will issue a diagnostic
|
|
and continue processing the remaining arguments.
|
|
.Sh SEE ALSO
|
|
.Xr dd 1 ,
|
|
.Xr touch 1 ,
|
|
.Xr truncate 2
|
|
.Sh STANDARDS
|
|
The
|
|
.Nm
|
|
utility conforms to no known standards.
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
utility first appeared in
|
|
.Fx 4.2 .
|
|
.Sh AUTHORS
|
|
The
|
|
.Nm
|
|
utility and this manual page were written by
|
|
.An Sheldon Hearn
|
|
.Aq sheldonh@uunet.co.za .
|