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Added section on file metadata use for renaming tokens.
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@tundra tundra authored on 29 Mar 2010
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 tren.rst
Currently, **tren** defines a number of renaming tokens. Future
releases of **tren** may add more of these, so it's good to
periodically reread this material.
 
File Attribute renaming tokens
How **tren** Uses File Metadata
================================
 
Files and directories have so-called "metadata" associated with them
like who owns them, how long they are, what date they were modified,
and so on. (This information is commonly described in a data structure
called ``stat``. Even non-Unix systems like Windows have some version
of this data structure.)
 
The file attribute- and sequence renaming tokens are built on this
metadata, so it's worth taking a moment to understand just *how*
it is used. **tren** keeps track of the following information
for every file- or directory you've named on the command line:
 
- The order the file appears on *the command line*
- The order the file appears *alphabetically*
- The *original name* of the file before any renaming took place
- The date/time it was last *accessed*
- The date/time it was last *modified*
- The date/time it's directory entry (inode) was last *modified*
- The *inode number* for the file
- The *device number* where the directory entry (inode) lives
- The *numeric group ID* the file belongs to
- The *name of the group* the file belongs to
- The *numeric user ID* of the file owner
- The *name of the user* that owns the file
- The *mode or permissions* for the file
- The *number of links* to the file
- The *size* of the file
 
 
**tren** uses this information to resolve file attribute renaming
tokens, compute the value of a particular sequence renaming token and
so on. For example, a sequence renaming token based on group *name*
will order the sequence *alphabetically by group name* whereas one
based on *group ID* will order it numerically.
 
It is likely that you'll only be interested in a small subset of
these. For completness, though, **tren** keeps track of all the
metadata available about the files- or directories named on the
command line and makes it available in the form of renaming tokens.
 
Most commonly, you'll find yourself using the command line,
alphabetic, original name, length, and various time/date renaming
tokens. Since there are actually three different kinds of date stamps
maintained in modern filesystems, it's worth knowing the difference
between them. A good tutorial can be found here:
 
http://chandynasty.blogspot.com/2007/01/difference-between-unix-mtime-ctime.html
 
.. NOTE:: **tren** is portable across many operating systems because
it is written in the Python programming language. Python
*mostly* works the exact same way everywhere. However,
Windows presents some problems because it does not quite
work the same way as Unix-derived OSs do. In particular, if
you need to make use of the User/Group ID/Name renaming
tokens on Windows, consider installing the ``win32all``
extensions to your Windows Python installation. If you
don't, **tren** will base its order on the generic names
"WindowsUser" and "WindowsGroup".
 
 
File Attribute Renaming Tokens
==============================
 
These tokens are derived from information about the file or
directory being renamed.
-----------------------------
 
::
 
$Id: tren.rst,v 1.159 2010/03/29 17:40:19 tundra Exp $
$Id: tren.rst,v 1.160 2010/03/29 18:44:06 tundra Exp $
 
You can find the latest version of this program at:
 
http://www.tundraware.com/Software/tren