cmp (GNU diffutils) - compare two files or byte ranges
cmp [-clsv] [-i NUM] [--help] [--print-chars] [--ignore-initial=NUM]
[--verbose] [--quiet] [--silent] [--version] -I FILE1 [FILE2 [RANGE1
[RANGE2]]]
The cmp utility compares two files of any type and writes the results
to the standard output. By default, cmp is silent if the files are the
same; if they differ, the byte and line number at which the first difference
occurred is reported.
In the output, bytes and lines are numbered beginning with one; however,
range inputs are zero-based; see below for details. A filename
of - represents standard input.
The following options are available:
-c, --print-chars
Output the differing bytes as characters, rather than as octal
numbers. Non-printable characters will be shown in form.
-i NUM, --ignore-initial=NUM
Ignore NUM initial characters from each file. This is a synonym
for specifying NUM NUM as the two RANGE arguments.
-l, --verbose
Print the byte number (decimal) and the differing byte values
(octal) for each difference.
-s, --quiet, --silent
Print nothing for differing files; return exit status only.
-v, --version
Print the diffutils version number.
The two optional arguments RANGE1 and RANGE2 represent byte ranges to
compare within the files. Each range can be expressed in several ways:
M+N Skip M bytes at the beginning of the input, then compare a maximum
of N bytes.
M-N, M,N
Skip M bytes at the beginning of the input, and read between
bytes M and N, which are both zero-based.
In either case, both M and N are optional and default to beginning and
end of file, respectively. In addition, they can be expressed in decimal,
octal (0NNN) or hexadecimal (0xNNN) form.
The zero-based range numbers may seem inconsistent with cmp output,
which is one-based; this is for compatibility with some versions of cmp
which allow "skip N bytes" parameters after the filenames; in this context,
the N is zero-based.
The cmp utility exits with one of the following values:
0 The files or byte ranges are identical.
1 The files or byte ranges are different; this includes the case
where one file or range is identical to the first part of the
other. In the latter case, if -s has not been specified, cmp
writes to standard output that EOF was reached in the shorter
file.
>1 An error occurred.
diff(1), diff3(1)
The cmp utility is expected to be POSIX 1003.2-compliant.
GNU Project 1998 September 23 CMP(1)
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