f66b9b40f4
This is compatible with GNU cmp. Reviewed by: bapt, markj (earlier version) Sponsored by: Klara, Inc. Differential Revision: https://reviews.freebsd.org/D32074
214 lines
5.4 KiB
Groff
214 lines
5.4 KiB
Groff
.\" Copyright (c) 1987, 1990, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the Institute of Electrical and Electronics Engineers, Inc.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)cmp.1 8.1 (Berkeley) 6/6/93
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.\" $FreeBSD$
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.\"
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.Dd September 23, 2021
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.Dt CMP 1
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.Os
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.Sh NAME
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.Nm cmp
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.Nd compare two files
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.Sh SYNOPSIS
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.Nm
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.Op Fl l | s | x
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.Op Fl bhz
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.Op Fl -ignore-initial Ns Cm = Ns Ar num1 Ns Op :num2
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.Op Fl -bytes Ns Cm = Ns Ar num
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.Ar file1 file2
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.Op Ar skip1 Op Ar skip2
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.Sh DESCRIPTION
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The
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.Nm
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utility compares two files of any type and writes the results
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to the standard output.
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By default,
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.Nm
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is silent if the files are the same; if they differ, the byte
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and line number at which the first difference occurred is reported.
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.Pp
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Bytes and lines are numbered beginning with one.
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.Pp
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The following options are available:
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.Bl -tag -width indent
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.It Fl b , Fl -print-bytes
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Print each byte when a difference is found.
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.It Fl h
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Do not follow symbolic links.
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.It Fl i Ar num1 Ns Oo :num2 Oc , Fl -ignore-initial= Ns Ar num1 Ns Op :num2
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Skip
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.Ar num1
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bytes from
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.Ar file1 ,
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and optionally skip
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.Ar num2
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bytes from
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.Ar file2 .
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If
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.Ar num2
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is not specified, then
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.Ar num1
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is applied for both
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.Ar file1
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and
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.Ar file2 .
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.It Fl l , Fl -verbose
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Print the byte number (decimal) and the differing
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byte values (octal) for each difference.
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.It Fl n Ar num , Fl -bytes= Ns num
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Only compare up to
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.Ar num
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bytes.
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.It Fl s , Fl -silent , Fl -quiet
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Print nothing for differing files; return exit
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status only.
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.It Fl x
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Like
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.Fl l
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but prints in hexadecimal and using zero as index
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for the first byte in the files.
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.It Fl z
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For regular files compare file sizes first, and fail the comparison if they
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are not equal.
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.El
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.Pp
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The optional arguments
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.Ar skip1
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and
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.Ar skip2
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are the byte offsets from the beginning of
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.Ar file1
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and
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.Ar file2 ,
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respectively, where the comparison will begin.
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The offset is decimal by default, but may be expressed as a hexadecimal
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or octal value by preceding it with a leading ``0x'' or ``0''.
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.Pp
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.Ar skip1
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and
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.Ar skip2
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may also be specified with SI size suffixes.
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.Sh EXIT STATUS
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The
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.Nm
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utility exits with one of the following values:
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.Bl -tag -width 4n
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.It 0
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The files are identical.
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.It 1
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The files are different; this includes the case
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where one file is identical to the first part of
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the other.
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In the latter case, if the
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.Fl s
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option has not been specified,
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.Nm
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writes to standard error that EOF was reached in the shorter
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file (before any differences were found).
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.It >1
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An error occurred.
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.El
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.Sh EXAMPLES
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Assuming a file named
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.Pa example.txt
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with the following contents:
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.Bd -literal -offset indent
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a
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b
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c
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.Ed
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.Pp
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Compare stdin with
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.Pa example.txt :
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.Bd -literal -offset indent
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$ echo -e "a\\nb\\nc" | cmp - example.txt
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.Ed
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.Pp
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Same as above but introducing a change in the third byte of stdin.
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Show the byte number (decimal) and differing byte (octal):
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.Bd -literal -offset indent
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$ echo -e "a\\nR\\nc" | cmp -l - example.txt
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3 122 142
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.Ed
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.Pp
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Compare file sizes of
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.Pa example.txt
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and
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.Pa /boot/loader.conf
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and return 1 if they are not equal.
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Note that
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.Fl z
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can only be used with regular files:
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.Bd -literal -offset indent
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$ cmp -z example.txt /boot/loader.conf
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example.txt /boot/loader.conf differ: size
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.Ed
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.Pp
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Compare stdin with
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.Pa example.txt
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omitting the first 4 bytes from stdin and the first 2 bytes from
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.Pa example.txt :
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.Bd -literal -offset indent
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$ echo -e "a\\nR\\nb\\nc" | cmp - example.txt 4 2
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.Ed
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.Sh SEE ALSO
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.Xr diff 1 ,
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.Xr diff3 1
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.Sh STANDARDS
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The
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.Nm
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utility is expected to be
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.St -p1003.2
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compatible.
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The
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.Fl b ,
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.Fl h ,
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.Fl i ,
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.Fl n ,
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.Fl x ,
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and
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.Fl z
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options are extensions to the standard.
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.Ar skip1
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and
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.Ar skip2
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arguments are extensions to the standard.
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.Sh HISTORY
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A
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.Nm
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command appeared in
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.At v1 .
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.Sh BUGS
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The phrase
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.Dq SI size suffixes
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above refers to the traditional power of two convention, as described in
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.Xr expand_number 3 .
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