# What’s the name of this file

One might want this so as to automatically generate a page header or footer recording what file is being processed. It’s not easy…

TeX retains what it considers the name of the job, only, in the primitive \jobname; this is the name of the file first handed to TeX, stripped of its directory name and of any extension (such as tex). If no file was passed (i.e., you’re using TeX interactively), \jobname has the value texput (the name that’s given to log files in this case).

This is fine, for the case of a small document, held in a single file; most significant documents will be held in a bunch of files, and TeX makes no attempt to keep track of files input to the job. So the user has to keep track, himself — the only way is to patch the input commands and cause them to retain details of the file name. This is particularly difficult in the case of Plain TeX, since the syntax of the \input command is so peculiar.

In the case of LaTeX, the input commands have pretty regular syntax, and the simplest patching techniques can be used on them. (Note that LaTeX’s \input command is itself a patch on top of the Plain TeX command. Our patches apply to the LaTeX version of the command, which is used as \input{file})

%%

%% \def\ThisFile{\jobname}
%% \let\OldInput\input
%% \renewcommand{\input}[1]{%
%%   \renewcommand{\ThisFile}{#1}%
%%   \OldInput#1%
%% }
%% 
%%
%% \documentclass{article}
%% ... (macros above)
%% \begin{document}
%% \input{preamble}
%%
%% \input{postamble}
%% \end{document}
%% 

%%

%% \def\ThisFile{\jobname}
%% \newcounter{FileStack}
%% \let\OrigInput\input
%% \renewcommand{\input}[1]{%
%%   \stackinput{#1}{\OrigInput}%
%% }
%% \newcommand{\stackinput}[2]{%
%%   \stepcounter{FileStack}%
%%   \expandafter\let
%%     \csname NameStack\theFileStack\endcsname
%%     \ThisFile
%%   \def\ThisFile{#1}%
%%   #2#1%
%%   \expandafter\let\expandafter
%%     \ThisFile
%%     \csname NameStack\theFileStack\endcsname
%% }
%% 
%%
%% \let\OrigInclude\include
%% \renewcommand{\include}[1]{%
%%   \stackinput{#1}{\OrigInclude}%
%% }
%% 

It is possible to keep track of the name of the file currently being processed, but it’s surprisingly difficult (these FAQs offered code, for a long time, that just didn’t work in many cases).

The currfile package provides a regular means of keeping track of the details of the current file (its name in \currfilename, directory in \currfiledir, as well as the file ‘base’ name (less its extension) and its extension). Currfile does this with the help of a second package, filehook, which spots file operations that use \input, \InputIfFileExists and \include, as well as package and class loading.

The FiNK (“File Name Keeper”) package keeps track of the file name and extension, in a macro \finkfile. FiNK is now deprecated, in favour of currfile, but remains available for use in old documents. %%

%% \def\striptexext#1.tex{#1}
%% ...
%% \edef\ThisFile{\expandafter\stripext\finkfile}
%% 
The FiNK bundle includes a fink.el that provides support under emacs with AUC-TeX.
currfile.sty
currfile
filehook.sty
filehook
fink.sty
fink