NAME
cmp —
compare two files
SYNOPSIS
cmp |
[-c]
[-l | -s]
file1 file2
[skip1
[skip2]] |
DESCRIPTION
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.
Bytes and lines are numbered beginning with one.
The following options are available:
-
-
- -c
- Do the compare using
getc(3) rather than
mmap(2). Combined with the
-l flag, this can be helpful in locating an I/O error in
the underlying device.
-
-
- -l
- Print the byte number (decimal) and the differing byte
values (octal) for each difference.
-
-
- -s
- Print nothing for differing files; return exit status
only.
The optional arguments
skip1 and
skip2 are the byte offsets from the beginning of
file1 and
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''.
EXIT STATUS
The
cmp utility exits with one of the following values:
-
-
- 0
- The files are identical.
-
-
- 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 -s option has not been specified,
cmp writes to standard output that EOF was reached in
the shorter file (before any differences were found).
-
-
- >1
- An error occurred.
SEE ALSO
comm(1),
diff(1),
diff3(1),
sdiff(1)
STANDARDS
The
cmp utility is expected to be
IEEE Std
1003.2 (“POSIX.2”) compatible.
HISTORY
The
cmp utility first appeared in
Version 1 AT&T UNIX.