fileSnapshot takes a snapshot of a selection of files,
recording summary information about each. changedFiles
compares two snapshots, or compares one snapshot to the current state
of the file system. The snapshots need not be the same directory;
this could be used to compare two directories.
fileSnapshot(path = ".", file.info = TRUE, timestamp = NULL,
md5sum = FALSE, digest = NULL, full.names = length(path) > 1,
...) changedFiles(before, after, path = before$path, timestamp = before$timestamp,
check.file.info = c("size", "isdir", "mode", "mtime"),
md5sum = before$md5sum, digest = before$digest,
full.names = before$full.names, ...)
# S3 method for fileSnapshot
print(x, verbose = FALSE, ...)
# S3 method for changedFiles
print(x, verbose = FALSE, ...)
character vector; the path(s) to record.
logical; whether to record file.info
values for each file.
character string or NULL; the name of a file
to write at the time the snapshot is taken. This gives a quick test
for modification, but may be unreliable; see the Details.
logical; whether MD5 summaries of each file should be taken as part of the snapshot.
a function or NULL; a function with header
function(filename) which will take a vector of filenames and
produce a vector of values of the same length, or a matrix with that
number of rows.
logical; whether full names (as in
list.files) should be recorded. Must be TRUE if
length(path) > 1.
additional parameters to pass to
list.files to control the set of files in the snapshots.
objects produced by fileSnapshot; two
snapshots to compare. If after is missing, a new snapshot of
the current file system will be produced for comparison, using
arguments recorded in before as defaults.
character vector; which columns from
file.info should be compared.
the object to print.
logical; whether to list all data when printing.
fileSnapshot returns an object of class "fileSnapshot".
This is a list containing the fields
a data frame whose rownames are the filenames, and whose columns contain the requested snapshot data
the normalized path from the call
a record of the other arguments from the call
other arguments passed via ... to
list.files.
changedFiles produces an object of class "changedFiles". This is a list containing
character vectors of filenames from the before and after snapshots, with obvious meanings
a logical matrix with a row for each common file, and a
column for each comparison test. TRUE indicates a change in
that test.
print methods are defined for each of these types. The print method for "fileSnapshot" objects displays the arguments used to produce them, while the one for "changedFiles" displays the added, deleted and changed fields if non-empty, and a submatrix of the changes matrix containing all of the TRUE values.
The fileSnapshot function uses list.files to
obtain a list of files, and depending on the file.info,
md5sum, and digest arguments, records information about
each file.
The changedFiles function compares two snapshots.
If the timestamp argument to fileSnapshot is length 1, a
file with that name is created. If it is length 1 in
changedFiles, the file_test function is used to
compare the age of all files common to both before and
after to it. This test may be unreliable: it compares the
current modification time of the after files to the timestamp;
that may not be the same as the modification time when the
after snapshot was taken. It may also give incorrect results
if the clock on the file system holding the timestamp differs from the
one holding the snapshot files.
If the check.file.info argument contains a non-empty character
vector, the indicated columns from the result of a call to
file.info will be compared.
If md5sum is TRUE, fileSnapshot will call the
tools::md5sum function to record the 32 byte MD5
checksum for each file, and changedFiles will compare the
values. The digest argument allows users to provide their own
digest function.
# Create some files in a temporary directory
dir <- tempfile()
dir.create(dir)
writeBin(1L, file.path(dir, "file1"))
writeBin(2L, file.path(dir, "file2"))
dir.create(file.path(dir, "dir"))
# Take a snapshot
snapshot <- fileSnapshot(dir, timestamp = tempfile("timestamp"), md5sum=TRUE)
# Change one of the files.
writeBin(3L:4L, file.path(dir, "file2"))
# Display the detected changes. We may or may not see mtime change...
changedFiles(snapshot)
changedFiles(snapshot)$changes
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