R.utils (version 1.5.0)

filePath: Construct the path to a file from components and expands Windows Shortcuts along the pathname from root to leaf

Description

Construct the path to a file from components and expands Windows Shortcuts along the pathname from root to leaf. This function is backward compatible with file.path() when argument removeUps=FALSE and expandLinks="none", except that a (character) NA is return if any argument is NA. This function exists on all platforms, not only Windows systems.

Usage

## S3 method for class 'default':
filePath(..., fsep=.Platform$file.sep, removeUps=TRUE, expandLinks=c("none", "any", "local", "relative", "network"), mustExist=FALSE, verbose=FALSE)

Arguments

...

Arguments to be pasted together to a file path and then be parsed from the root to the leaf where Windows shortcut files are recognized and expanded according to argument which in each step.

fsep

the path separator to use.

removeUps

If TRUE, relative paths, for instance "foo/bar/../" are shortend into "foo/", but also "./" are removed from the final pathname, if possible.

expandLinks

A character string. If "none", Windows Shortcut files are ignored. If "local", the absolute target on the local file system is used. If "relative"

mustExist

If TRUE and if the target does not exist, the original pathname, that is, argument pathname is returned. In all other cases the target is returned.

verbose

If TRUE, extra information is written while reading.

Value

• Returns a character string.

On speed

Internal file.exists() is call while expanding the pathname. This is used to check if there exists a Windows shortcut file named 'foo.lnk' in 'path/foo/bar'. If it does, 'foo.lnk' has to be followed, and in other cases 'foo' is ordinary directory. The file.exists() is unfortunately a bit slow, which is why this function appears slow if called many times.

Details

If expandLinks==TRUE, each component, call it parent, in the absolute path is processed from the left to the right as follows: 1. If a "real" directory of name parent exists, it is followed. 2. Otherwise, if Microsoft Windows Shortcut file with name parent.lnk exists, it is read. If its local target exists, that is followed, otherwise its network target is followed. 3. If no valid existing directory was found in (1) or (2), the expanded this far followed by the rest of the pathname is returned quietly. 4. If all of the absolute path was expanded successfully the expanded absolute path is returned.

See Also

readWindowsShortcut(). file.path().

Examples

# Default
print(file.path("foo", "bar", "..", "name")) # "foo/bar/../name"

# Shorten pathname, if possible
print(filePath("foo", "bar", "..", "name"))  # "foo/name"
print(filePath("foo/bar/../name"))           # "foo/name"

# Recognize Windows Shortcut files along the path, cf. Unix soft links
filename <- system.file("data-ex/HISTORY.LNK", package="R.utils")
print(filename)
filename <- filePath(filename, expandLinks="relative")
print(filename)