[texhax] How to insert file content into a string?

[Uwe Lück]

At 19:06 04.11.06, Micha Hofri wrote:

>   We work on a book, and many versions of typeset sections fly back and
>forth.  We would like to insert in the output of latex the time the
>compiled file was last modified, ideally into the header or footer.  I am
>on a Unix system and can get the string , say "Nov 4 13:05" into a file,
>say filedate, which I could then read with \input{filedate}.
>
>Printing it once is easy, but how can I get it into a header
>definition?  Currently that definition includes the predefined \today, so
>it would be enough if I could use this new string in, say, a
>\renewcommand{\today}{...here...}?

[This time from my mind, without checking, so may be wrong:]

Approach no. 1:

The input files `foo.tex' should contain \ProvidesFile{foo}[2006/...].
After \GetFileInfo{foo} from the doc package, \filedate expands
to an alternative to \today that you probably desire.
So replace your \today in your header definition by \filedate.

Disadvantage: I experience day by day that I forget to update
the date in \Provides... ...

OK, a version control system may help here ...

Approach no. 2:

Use the actual "last change" information from the operating
system(s) -- namely [abbreviated]:

ls foo*.tex | fileinfo.log

i.e., pipe a file listing to fileinfo.log. In compiling the most recent
draft version of the entire work, read fileinfo.log with a parsing macro
that defines \timeoffile{foo} to be the "last change" time
for foo.tex. Right before inputting foo.tex, \def\actualinputfile{foo.tex}.
Use \timeoffile{\actualinputfile} instead of your \today in your
definition of the page header.

I think much that there should be a package for drafts and revising
with facilities like these. Some packages contribute to this goal,
but there should be a package merging such approaches.

I have thought on an own package for listing file version informations
-- but these thoughts may be irrelevant for your task.
There is a similar package for making use of file version informations
on

     CTAN:/macros/latex/dateiliste

HTH -- Uwe.