@dfn{message-digest}) for each specified @var{file}.
If a @var{file} is specified as @samp{-} or if no files are given
@code{md5sum} computes the checksum for the standard input.
-@code{md5sum} can also determine whether
-a file's checksum has changed. Synopsis:
+@code{md5sum} can also determine whether a file and checksum are
+consistent. Synopsis:
@example
md5sum [@var{option}]@dots{} [@var{file}]@dots{}
md5sum [@var{option}]@dots{} --check [@var{file}]
-md5sum [@var{option}]@dots{} --string=@var{string}@dots{}
+md5sum [@var{option}]@dots{} --string=@var{string} @dots{}
@end example
For each @var{file}, @samp{md5sum} outputs the MD5 checksum, a flag
indicating a binary or text input file, and the filename.
+If @var{file} is omitted or specified as @samp{-}, standard input is read.
The program accepts the following options. Also see @ref{Common options}.
@opindex -b
@opindex --binary
@cindex binary input files
-Treat input files as binary. This makes no difference on Unix systems,
-but other systems have different internal and external character
-representations, notably to mark end-of-line.
+Treat all input files as binary. This option has no effect on Unix
+systems, since they don't distinguish between binary and text files.
+This option is useful on systems that have different internal and
+external character representations.
@item -c
@itemx --check
each named file and the corresponding checksum data are consistent.
The input to this mode of @code{md5sum} is usually the output of
a prior, checksum-generating run of @samp{md5sum}.
-Each recognized line of input consists of an MD5 checksum, a binary/text
+Each valid line of input consists of an MD5 checksum, a binary/text
flag, and then a filename.
-The file will be opened (with each possible relative path) and the its
-message-digest computed. If this computed message digest is not the
-same as that given in the line, the file will be marked as failed.
+Binary files are marked with @samp{*}, text with @samp{ }.
+For each such line, @code{md5sum} reads the named file and computes its
+MD5 checksum. Then, if the computed message digest does not match the
+one on the line with the filename, the file is noted as having
+failed the test. Otherwise, the file passes the test.
@item -s
@itemx --string=@var{string}
@opindex -s
@opindex --string
Compute the message digest for @var{string}, instead of for a file. The
-result is the same as for a file with contains exactly @var{string}.
+result is the same as for a file that contains exactly @var{string}.
@item -t
@itemx --text
@cindex text input files
Treat all input files as text files. This is the reverse of
@samp{--binary}.
+
@item -v
@itemx --verbose
@opindex -v