File Uri Scheme and Relative Files

Question

Assume that the scheme for a uri is "file". Also assume that the path starts with '.'

An example path is './.bashrc'. How would the fulluri look? 'file://./.bashrc' appears odd to me.

Answer 1

In short, a file URL takes the form of:

file://localhost/absolute/path/to/file [ok] 

or you can omit the host (but not the slash):

file:///absolute/path/to/file [ok] 

but not this:

file://file_at_current_dir [no way] 

nor this:

file://./file_at_current_dir [no way] 

I just confirmed that via Python's urllib2.urlopen()

More detail from http://en.wikipedia.org/wiki/File_URI_scheme:

"file:///foo.txt" is okay, while "file://foo.txt" is not, although some interpreters manage to handle the latter 

Answer 2

It's impossible to use full file: URI with '.' or '..' segments in path without root part of that path. Whether you use 'file://./.bashrc' or 'file:///./.bashrc' these paths will have no sense. If you want to use a relative link, use it without protocol/authority part:

<a href="./.bashrc">link</a> 

If you want to use full URI, you must tell a root relative to which your relative path is:

<a href="file:///home/kindrik/./.bashrc">link</a> 

According to RFC 3986

The path segments "." and "..", also known as dot-segments, are defined for relative reference within the path name hierarchy.  They are intended for use at the beginning of a relative-path reference (Section 4.2) to indicate relative position within the hierarchical tree of names.  This is similar to their role within some operating systems' file directory structures to indicate the current directory and parent directory, respectively.  However, unlike in a file system, these dot-segments are only interpreted within the URI path hierarchy and are removed as part of the resolution process (Section 5.2).  The complete path segments "." and ".." are intended only for use within relative references (Section 4.1) and are removed as part of the reference resolution process (Section 5.2).  However, some deployed implementations incorrectly assume that reference resolution is not necessary when the reference is already a URI and thus fail to remove dot-segments when they occur in non-relative paths.  URI normalizers should remove dot-segments by applying the remove_dot_segments algorithm to the path, as described in Section 5.2.4.  The complete path segments "." and ".." are intended only for use within relative references (Section 4.1) and are removed as part of the reference resolution process (Section 5.2)  

RFC 3986 describes even an algorithm of removing these "." and ".." from URI.