.\"	$NetBSD: cmp.1,v 1.12 2016/12/14 15:24:06 abhinav Exp $
.\"
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.\"     @(#)cmp.1	8.1 (Berkeley) 6/6/93
.\"
.Dd December 13, 2016
.Dt CMP 1
.Os
.Sh NAME
.Nm cmp
.Nd compare two files
.Sh SYNOPSIS
.Nm
.Op Fl c
.Op Fl l | Fl s
.Ar file1 file2
.Op Ar skip1 Op Ar skip2
.Sh DESCRIPTION
The cmp utility compares two files of any type and writes the results
to the standard output.
By default,
.Nm
is silent if the files are the same; if they differ, the byte
and line number at which the first difference occurred is reported.
.Pp
Bytes and lines are numbered beginning with one.
.Pp
The following options are available:
.Bl -tag -width flag
.It Fl c
Do the compare using
.Xr getc 3
rather than
.Xr mmap 2 .
Combined with the
.Fl l
flag, this can be helpful in locating an I/O error in the underlying
device.
.It Fl l
Print the byte number (decimal) and the differing
byte values (octal) for each difference.
.It Fl s
Print nothing for differing files; return exit
status only.
.El
.Pp
The optional arguments
.Ar skip1
and
.Ar skip2
are the byte offsets from the beginning of
.Ar file1
and
.Ar file2 ,
respectively, where the comparison will begin.
The offset is decimal by default, but may be expressed as an hexadecimal
or octal value by preceding it with a leading ``0x'' or ``0''.
.Sh EXIT STATUS
The
.Nm
utility exits with one of the following values:
.Bl -tag -width 4n
.It 0
The files are identical.
.It 1
The files are different; this includes the case
where one file is identical to the first part of
the other.
In the latter case, if the
.Fl s
option has not been specified,
.Nm
writes to standard output that EOF was reached in the shorter
file (before any differences were found).
.It \*[Gt]1
An error occurred.
.El
.Sh SEE ALSO
.Xr comm 1 ,
.Xr diff 1 ,
.Xr diff3 1 ,
.Xr sdiff 1
.Sh STANDARDS
The
.Nm
utility is expected to be
.St -p1003.2
compatible.
.Sh HISTORY
The
.Nm
utility first appeared in
.At v1 .