Compute the 32-byte MD5 hashes of one or more files.
Usage
md5sum(files)
Arguments
files
character. The paths of file(s) whose contents are to be hashed.
Value
A character vector of the same length as files, with names
equal to files. The elements will be NA for non-existent
or unreadable files, otherwise a 32-character string of hexadecimal
digits.
Source
The underlying C code was written by Ulrich Drepper and extracted from
a 2001 release of glibc.
Details
A MD5 ‘hash’ or ‘checksum’ or ‘message digest’ is
a 128-bit summary of the file contents represented by 32 hexadecimal
digits. Files with different MD5 sums are different: only very
exceptionally (and usually with the intent to deceive) are those with
the same sums different.
On Windows all files are read in binary mode (as the md5sum
utilities there do): on other OSes the files are read in the default
mode (almost always text mode where there is more than one).
MD5 sums are used as a check that R packages have been unpacked
correctly and not subsequently modified.