# md5sum

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##### Compute MD5 Checksums

Compute the 32-byte MD5 hashes of one or more files.

Keywords
utilities
##### Usage
md5sum(files)
##### Arguments
files

character. The paths of file(s) whose contents are to be hashed.

##### 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.

##### Value

A character vector of the same length as files, with names equal to files (possibly expanded). The elements will be NA for non-existent or unreadable files, otherwise a 32-character string of hexadecimal digits.

checkMD5sums
library(tools) # NOT RUN { as.vector(md5sum(dir(R.home(), pattern = "^COPY", full.names = TRUE))) # }