What is the “/.vol” directory for?

Question

In Mac OS X, what is the /.vol directory for? I noticed that Excel usually reverences files (while investigating in instruments) using a /.vol path. Is it a folder for temporary files, or does it contain links to all files in the volume?

If so, how can I reference a file via its /.vol path?

Answer 1

Per this page about invisible files on Mac OS X:

This pseudo-directory is used to access files by their ID number (aka inode number) rather than by name. For example, /.vol/234881034/105486 is file #105486 on volume #234881034.file #105486 on volume #234881034.

You can find the volume id and inode using stat. An example, using /etc/hosts:

$ head -3 /etc/hosts
##
# Host Database
#

$ stat /etc/hosts
234881026 23347035 -rw-r--r-- 1 root wheel 0 1035 "Jul 15 10:11:35 2010" "May 30 20:55:10 2010" "May 30 20:55:11 2010" "May 30 20:47:32 2010" 4096 8 0 /etc/hosts

$ head -3 /.vol/234881026/23347035
##
# Host Database
#