Under what circumstances might [pwd] fail to return a result? I would have assumed it would be guaranteed to return a path without error - but the result below shows otherwise. (on FreeBSD 4.9-STABLE tcl8.4.4 tclkit)

 error getting working directory name: no such file or directory
     while executing
 "pwd"
     (in namespace eval "::math" script line 20)
     invoked from within
 "namespace eval ::math {

     variable version 1.2.2

     # misc.tcl

     namespace export    cov             fibonacci       integrate
     namespace export    max             mean            min..."
     (file "/root/shelltests/nefualert.vfs/lib/tcllib1.5/math/math.tcl" line 15)
     invoked from within
 "source /root/shelltests/nefualert.vfs/lib/tcllib1.5/math/math.tcl"
     ("package ifneeded" script)
     invoked from within
 "package require math"

update: The circumstance giving rise to the above was a situation where the directory was deleted and recreated by another process. A little suprising... but perhaps not unreasonable. A bit more suprising is that if from within the tcl process you use [file delete] & [file mkdir] then [pwd] is still unable to return a result. ...Not that I can think of a really good reason why one would need to delete & recreate dirs underneath oneself - but perhaps whilst manually experimenting & shuffling around directory trees of alternate datafiles under a running process, it may catch you unawares as it did me.

DKF: That's just classic UNIX filesystem semantics. Think of it like this: every process has a reference to its current directory, and (like other kinds of files) directories are only really deleted when their reference count drops to zero. However, discovering the name of the directory is more complex, because that requires reference to the containing directory tree, and if that doesn't have a reference to the dir, you can't find out what its name is. Networked filesystems such as NFS and AFS do not work this way because making reference counting work across a network is really hard, and neither do non-UNIX platforms (especially Windows). SMB is covered by both of these rules. :^)

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AMG: On Windows, how do I get the current working directory for each volume? I want to know how to normalize a "volumerelative" path using Tcl 8.3.5. If [pwd] returns C:/foo, how do I deal with A:bar? Newer versions of Tcl have [file normalize], but I have no such luxuries.