Abstract Symbolic links make the Unix file system non-hierarchical, resulting in multiple valid path names for a given file. This ambiguity is a source of confusion, especially since some shells work overtime to present a consistent view from programs such as pwd, while other programs and the kernel itself do nothing about the problem. Plan 9 has no symbolic links but it does have other mechanisms that produce the same difficulty. Moreover, Plan 9 is founded on the ability to control a program's environment by manipulating its name space.
Ambiguous names muddle the result of operations such as copying a name space across the network.
The definition of 'accurate' is that the path name for a file is guaranteed to be the rooted, absolute name the program used to acquire it. Ambiguous situations are resolved by examining the lexically maintained names themselves. A new kernel call, fd2path, returns the file name associated with an open file, permitting the use of reliable names to improve system services ranging from pwd to debugging. Although this work was done in Plan 9, Unix systems could also benefit from the addition of a method to recover the accurate name of an open file or the current directory. View the full text of this paper in HTML form and PDF form.