1.\" Copyright (c) 1987, 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the Institute of Electrical and Electronics Engineers, Inc. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.Dd September 23, 2021 32.Dt CMP 1 33.Os 34.Sh NAME 35.Nm cmp 36.Nd compare two files 37.Sh SYNOPSIS 38.Nm 39.Op Fl l | s | x 40.Op Fl bhz 41.Op Fl -ignore-initial Ns Cm = Ns Ar num1 Ns Op :num2 42.Op Fl -bytes Ns Cm = Ns Ar num 43.Ar file1 file2 44.Op Ar skip1 Op Ar skip2 45.Sh DESCRIPTION 46The 47.Nm 48utility compares two files of any type and writes the results 49to the standard output. 50By default, 51.Nm 52is silent if the files are the same; if they differ, the byte 53and line number at which the first difference occurred is reported. 54.Pp 55Bytes and lines are numbered beginning with one. 56.Pp 57The following options are available: 58.Bl -tag -width indent 59.It Fl b , Fl -print-bytes 60Print each byte when a difference is found. 61.It Fl h 62Do not follow symbolic links. 63.It Fl i Ar num1 Ns Oo :num2 Oc , Fl -ignore-initial= Ns Ar num1 Ns Op :num2 64Skip 65.Ar num1 66bytes from 67.Ar file1 , 68and optionally skip 69.Ar num2 70bytes from 71.Ar file2 . 72If 73.Ar num2 74is not specified, then 75.Ar num1 76is applied for both 77.Ar file1 78and 79.Ar file2 . 80.It Fl l , Fl -verbose 81Print the byte number (decimal) and the differing 82byte values (octal) for each difference. 83.It Fl n Ar num , Fl -bytes= Ns num 84Only compare up to 85.Ar num 86bytes. 87.It Fl s , Fl -silent , Fl -quiet 88Print nothing for differing files; return exit 89status only. 90.It Fl x 91Like 92.Fl l 93but prints in hexadecimal and using zero as index 94for the first byte in the files. 95.It Fl z 96For regular files compare file sizes first, and fail the comparison if they 97are not equal. 98.El 99.Pp 100The optional arguments 101.Ar skip1 102and 103.Ar skip2 104are the byte offsets from the beginning of 105.Ar file1 106and 107.Ar file2 , 108respectively, where the comparison will begin. 109The offset is decimal by default, but may be expressed as a hexadecimal 110or octal value by preceding it with a leading ``0x'' or ``0''. 111.Pp 112.Ar skip1 113and 114.Ar skip2 115may also be specified with SI size suffixes. 116.Sh EXIT STATUS 117The 118.Nm 119utility exits with one of the following values: 120.Bl -tag -width 4n 121.It 0 122The files are identical. 123.It 1 124The files are different; this includes the case 125where one file is identical to the first part of 126the other. 127In the latter case, if the 128.Fl s 129option has not been specified, 130.Nm 131writes to standard error that EOF was reached in the shorter 132file (before any differences were found). 133.It >1 134An error occurred. 135.El 136.Sh EXAMPLES 137Assuming a file named 138.Pa example.txt 139with the following contents: 140.Bd -literal -offset indent 141a 142b 143c 144.Ed 145.Pp 146Compare stdin with 147.Pa example.txt : 148.Bd -literal -offset indent 149$ echo -e "a\\nb\\nc" | cmp - example.txt 150.Ed 151.Pp 152Same as above but introducing a change in the third byte of stdin. 153Show the byte number (decimal) and differing byte (octal): 154.Bd -literal -offset indent 155$ echo -e "a\\nR\\nc" | cmp -l - example.txt 156 3 122 142 157.Ed 158.Pp 159Compare file sizes of 160.Pa example.txt 161and 162.Pa /boot/loader.conf 163and return 1 if they are not equal. 164Note that 165.Fl z 166can only be used with regular files: 167.Bd -literal -offset indent 168$ cmp -z example.txt /boot/loader.conf 169example.txt /boot/loader.conf differ: size 170.Ed 171.Pp 172Compare stdin with 173.Pa example.txt 174omitting the first 4 bytes from stdin and the first 2 bytes from 175.Pa example.txt : 176.Bd -literal -offset indent 177$ echo -e "a\\nR\\nb\\nc" | cmp - example.txt 4 2 178.Ed 179.Sh SEE ALSO 180.Xr diff 1 , 181.Xr diff3 1 182.Sh STANDARDS 183The 184.Nm 185utility is expected to be 186.St -p1003.2 187compatible. 188The 189.Fl b , 190.Fl h , 191.Fl i , 192.Fl n , 193.Fl x , 194and 195.Fl z 196options are extensions to the standard. 197.Ar skip1 198and 199.Ar skip2 200arguments are extensions to the standard. 201.Sh HISTORY 202A 203.Nm 204command appeared in 205.At v1 . 206.Sh BUGS 207The phrase 208.Dq SI size suffixes 209above refers to the traditional power of two convention, as described in 210.Xr expand_number 3 . 211