\input texinfo
@setfilename kpathsea.info
@settitle Kpathsea: A library for path searching

@set version 6.0.0
@set month-year July 2010

@copying
This file documents the Kpathsea library for path searching.

Copyright @copyright{} 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
2004, 2005, 2007, 2008, 2009, 2010 Karl Berry & Olaf Weber.

Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries a copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).
@end ignore

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that this permission notice may be stated in a translation
approved by the @TeX{} Users Group.
@end copying

@c Define new indices for commands, filenames, and options.
@defcodeindex cm
@defcodeindex fl
@defcodeindex op

@c Put everything in one index (arbitrarily chosen to be the concept index).
@syncodeindex cm cp
@syncodeindex fl cp
@syncodeindex fn cp
@syncodeindex ky cp
@syncodeindex op cp
@syncodeindex pg cp
@syncodeindex tp cp
@syncodeindex vr cp

@dircategory TeX
@direntry
* Kpathsea: (kpathsea).                       File lookup along search paths.
* kpsewhich: (kpathsea)Invoking kpsewhich.    TeX file searching.
* mktexfmt: (kpathsea)mktex scripts.          Format (fmt/base/mem) generation.
* mktexlsr: (kpathsea)Filename database.      Update ls-R.
* mktexmf: (kpathsea)mktex scripts.           MF source generation.
* mktexpk: (kpathsea)mktex scripts.           PK bitmap generation.
* mktextex: (kpathsea)mktex scripts.          TeX source generation.
* mktextfm: (kpathsea)mktex scripts.          TeX font metric generation.
@end direntry


@titlepage
@title Kpathsea library
@subtitle for version @value{version}
@subtitle @value{month-year}
@author Karl Berry
@author Olaf Weber
@author Taco Hoekwater
@author @url{http://tug.org/kpathsea}

@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage


@contents


@ifnottex
@node Top
@top Kpathsea library

This manual documents how to install and use the Kpathsea library for
filename lookup.  It corresponds to version @value{version},
released in @value{month-year}.

@menu
* Introduction::                Overview.
* Installation::                Compilation, installation, and bug reporting.

* Path searching::              How filename lookups work.
* TeX support::                 Special support for TeX-related file lookups.

* Programming::                 How to use Kpathsea features in your program.

* Index::                       General index.
@end menu
@end ifnottex


@node Introduction
@chapter Introduction

@cindex introduction
@cindex fundamental purpose of Kpathsea

This manual corresponds to version @value{version} of the Kpathsea
library, released in @value{month-year}.

The library's fundamental purpose is to return a filename from a list of
directories specified by the user, similar to what shells do when
looking up program names to execute.

@cindex programs using the library
The following software, all of which we maintain, uses this library:

@itemize @bullet
@item Dviljk (see the @samp{dvilj} man page)
@item Dvipsk (@pxref{Top, , Introduction, dvips, Dvips: A DVI driver})
@item GNU font utilities (@pxref{Top, , Introduction, fontu, GNU font
utilities})
@item Web2c (@pxref{Top, , Introduction, web2c, Web2c: A @TeX{}
implementation})
@item Xdvik (see the @samp{xdvi} man page)
@end itemize

@noindent Other software that we do not maintain also uses it.

@cindex interface, not frozen
@cindex comments, making
@cindex suggestions, making
We are still actively maintaining the library (and probably always will
be, despite our hopes).  If you have comments or suggestions, please send
them to us (@pxref{Reporting bugs}).

@cindex conditions for use
@cindex license for using the library
@cindex GNU General Public License
We distribute the library under the GNU Library General Public License
(LGPL).  In short, this means if you write a program using the library,
you must (offer to) distribute the source to the library, along with any
changes you have made, and allow anyone to modify the library source and
distribute their modifications.  It does not mean you have to distribute
the source to your program, although we hope you will.  See the
accompanying files for the text of the GNU licenses.

@cindex @TeX{} Users Group
If you know enough about @TeX{} to be reading this manual, then you (or
your institution) should consider joining the @TeX{} Users Group (if
you're already a member, thanks!).  TUG produces the periodical
@cite{TUGboat}, sponsors an annual meeting and publishes the
proceedings, and arranges courses on @TeX{} for all levels of users
throughout the world.  See @url{http://tug.org} for information.

@menu
* History::
@end menu


@node History
@section History

@cindex history of Kpathsea

@cindex Knuth, Donald E.
(This section is for those people who are curious about how the library
came about.)  (If you like to read historical accounts of software, we
urge you to seek out the GNU Autoconf manual and the ``Errors of
@TeX{}'' paper by Don Knuth, published in @cite{Software---Practice and
Experience} 19(7), July 1989.)

@cindex Morgan, Tim
@cindex Rokicki, Tom
@cindex Berry, Karl
@cindex VAX 11/750
@cindex Sun 2
@pindex pxp @r{Pascal preprocessor}
@pindex pc @r{Pascal compiler}
[Karl writes.]  My first ChangeLog entry for Web2c seems to be February
1990, but I may have done some work before then.  In any case, Tim
Morgan and I were jointly maintaining it for a time.  (I should mention
here that Tim had made Web2c into a real distribution long before I had
ever used it or even heard of it, and Tom Rokicki did the original
implementation.  I was using @code{pxp} and @code{pc} on VAX 11/750's
and the hot new Sun 2 machines.)

It must have been later in 1990 and 1991 that I started working on
@cite{@TeX{} for the Impatient}. Dvips, Xdvi, Web2c, and the GNU
fontutils (which I was also writing at the time) all used different
environment variables, and, more importantly, had different bugs in
their path searching. This became extremely painful, as I was stressing
everything to the limit working on the book.  I also desperately wanted
to implement subdirectory searching, since I couldn't stand putting
everything in one big directory, and also couldn't stand having to
explicitly specify @file{cm}, @file{pandora}, @dots{} in a path.

@cindex Vojta, Paul
In the first incarnation, I just hacked separately on each
program---that was the original subdirectory searching code in both Xdvi
and Dvips, though I think Paul Vojta has completely rewritten Xdvi's
support by now.  That is, I tried to go with the flow in each program,
rather than changing the program's calling sequences to conform to
common routines.

Then, as bugs inevitably appeared, I found I was fixing the same thing
three times (Web2c and fontutils were always sharing code, since I
maintained those---there was no Dvipsk or Xdvik or Dviljk at this
point).  After a while, I finally started sharing source files.  They
weren't yet a library, though.  I just kept things up to date with shell
scripts.  (I was developing on a 386 running ISC 2.2 at the time, and so
didn't have symbolic links.  An awful experience.)

@cindex MacKenzie, David
The ChangeLogs for Xdvik and Dvipsk record initial releases of those
distributions in May and June 1992.  I think it was because I was tired
of the different configuration strategies of each program, not so much
because of the path searching.  (Autoconf was being developed by David
MacKenzie and others, and I was adapting it to @TeX{} and friends.)

@cindex zuhn, david
I started to make a separate library that other programs could link with
on my birthday in April 1993, according to the ChangeLog.  I don't
remember exactly why I finally took the time to make it a separate
library; a conversation with david zuhn that initiated it.  Just seemed
like it was time.

@cindex Walsh, Norman
@cindex Neumann, Gustaf
Dviljk got started in March 1994 after I bought a Laserjet 4.  (Kpathsea
work got suspended while Norm Walsh and I, with Gustaf Neumann's help,
implemented a way for @TeX{} to get at all those neat builtin LJ4 fonts
@dots{} such a treat to have something to typeset in besides Palatino!)

By spring of 1995, I had implemented just about all the path-searching
features in Kpathsea that I plan to, driven beyond my initial goals by
Thomas Esser and others.  I then started to integrate Web2c with
Kpathsea. After the release of a stable Web2c, I hope to be able to stop
development, and turn most of my attention back to making fonts for GNU.
(Always assuming Micros**t hasn't completely obliterated Unix by then,
or that software patents haven't stopped software development by anybody
smaller than a company with a million-dollar-a-year legal budget.  Which
is actually what I think is likely to happen, but that's another
story@dots{})

@cindex Weber, Olaf
[Olaf writes.]  At the end of 1997, UNIX is still alive and kicking,
individuals still develop software, and Web2c development still
continues.  Karl had been looking for some time for someone to take up
part of the burden, and I volunteered.


@include install.texi
@include hier.texi
@include unixtex.texi
@include bugs.texi


@node Path searching
@chapter Path searching

@cindex path searching

This chapter describes the generic path searching mechanism Kpathsea
provides.  For information about searching for particular file types
(e.g., @TeX{} fonts), see the next chapter.

@menu
* Searching overview::          Basic scheme for searching.
* Path sources::                Where search paths can be defined.
* Path expansion::              Special constructs in search paths.
* Filename database::           Using an externally-built list to search.
* Invoking kpsewhich::          Standalone path lookup.
@end menu


@node Searching overview
@section Searching overview

@cindex searching overview
@cindex path searching, overview
@cindex overview of path searching

@cindex search path, defined
A @dfn{search path} is a colon-separated list of @dfn{path elements},
which are directory names with a few extra frills.  A search path can
come from (a combination of) many sources; see below.  To look up a file
@samp{foo} along a path @samp{.:/dir}, Kpathsea checks each element of
the path in turn: first @file{./foo}, then @file{/dir/foo}, returning
the first match (or possibly all matches).

@cindex magic characters
@kindex : @r{may not be :}
@kindex / @r{may not be /}
The ``colon'' and ``slash'' mentioned here aren't necessarily @samp{:}
and @samp{/} on non-Unix systems.  Kpathsea tries to adapt to other
operating systems' conventions.

@cindex database search
@cindex searching the database
To check a particular path element @var{e}, Kpathsea first sees if a
prebuilt database (@pxref{Filename database}) applies to @var{e}, i.e.,
if the database is in a directory that is a prefix of @var{e}.  If so,
the path specification is matched against the contents of the database.

@cindex floating directories
@cindex filesystem search
@cindex disk search
@cindex searching the disk
If the database does not exist, or does not apply to this path element,
or contains no matches, the filesystem is searched (if this was not
forbidden by the specification with @samp{!!} and if the file being
searched for must exist).  Kpathsea constructs the list of directories
that correspond to this path element, and then checks in each for the
file being searched for.  (To help speed future lookups of files in the
same directory, the directory in which a file is found is floated to the
top of the directory list.)

@cindex must exist
@cindex VF files, not found
@flindex cmr10.vf
@findex \openin
The ``file must exist'' condition comes into play with VF files and
input files read by the @TeX{} @samp{\openin} command.  These files
might very well not exist (consider @file{cmr10.vf}), and so it would
be wrong to search the disk for them.  Therefore, if you fail to
update @file{ls-R} when you install a new VF file, it will not be
found.

Each path element is checked in turn: first the database, then the disk.
If a match is found, the search stops and the result is returned.  This
avoids possibly-expensive processing of path specifications that are
never needed on a particular run.  (Unless the search explicitly
requested all matches.)

@cindex expansion, path element
Although the simplest and most common path element is a directory name,
Kpathsea supports additional features in search paths: layered default
values, environment variable names, config file values, users' home
directories, and recursive subdirectory searching.  Thus, we say that
Kpathsea @dfn{expands} a path element, meaning transforming all the
magic specifications into the basic directory name or names.  This
process is described in the sections below.  It happens in the same
order as the sections.

@cindex absolute filenames
@cindex relative filenames
@cindex explicitly relative filenames
@cindex filenames, absolute or explicitly relative
Exception to all of the above: If the filename being searched for is
absolute or explicitly relative, i.e., starts with @samp{/} or @samp{./}
or @samp{../}, Kpathsea simply checks if that file exists.

@cindex permission denied
@cindex unreadable files
@cindex access warnings
@cindex warnings, file access
@flindex lost+found @r{directory}
@vindex TEX_HUSH
Ordinarily, if Kpathsea tries to access a file or directory that
cannot be read, it gives a warning.  This is so you will be alerted to
directories or files that accidentally lack any read permission (for
example, a @file{lost+found} directory).  If you prefer not to see
these warnings, include the value @samp{readable} in the
@code{TEX_HUSH} environment variable or config file value.

This generic path searching algorithm is implemented in
@file{kpathsea/pathsearch.c}.  It is employed by a higher-level
algorithm when searching for a file of a particular type (@pxref{File
lookup}, and @ref{Glyph lookup}).


@node Path sources
@section Path sources

@cindex path sources
@cindex sources for search paths

A search path can come from many sources.  In the order in which
Kpathsea uses them:

@enumerate
@item
@cindex environment variable, source for path
A user-set environment variable, e.g., @code{TEXINPUTS}.
Environment variables with an underscore and the program name appended
override; for example, @code{TEXINPUTS_latex} overrides @code{TEXINPUTS}
if the program being run is named @samp{latex}.

@item
A program-specific configuration file, e.g., an @samp{S /a:/b} line in
Dvips' @file{config.ps} (@pxref{Config files,,, dvips, Dvips}).

@item
@cindex configuration file, source for path
@cindex Kpathsea config file, source for path
@flindex texmf.cnf@r{, source for path}
A line in a Kpathsea configuration file @file{texmf.cnf}, e.g.,
@samp{TEXINPUTS=/c:/d} (see below).

@item
@cindex compilation value, source for path
The compile-time default (specified in @file{kpathsea/paths.h}).
@end enumerate

You can see each of these values for a given search path by using the
debugging options (@pxref{Debugging}).

These sources may be combined via default expansion (@pxref{Default
expansion}).

@menu
* Config files::        Kpathsea's runtime config files (texmf.cnf).
@end menu


@node Config files
@subsection Config files

@cindex config files
@flindex texmf.cnf@r{, definition for}

@cindex runtime configuration files
@vindex TEXMFCNF
As mentioned above, Kpathsea reads @dfn{runtime configuration files}
named @file{texmf.cnf} for search path and other definitions.  The
search path used to look for these configuration files is named
@code{TEXMFCNF}, and is constructed in the usual way, as described
above, except that configuration files cannot be used to define the
path, naturally; also, an @file{ls-R} database is not used to search for
them.

Kpathsea reads @emph{all} @file{texmf.cnf} files in the search path, not
just the first one found; definitions in earlier files override those in
later files.  Thus, if the search path is @samp{.:$TEXMF}, values from
@file{./texmf.cnf} override those from @file{$TEXMF/texmf.cnf}.

@vindex KPATHSEA_WARNING
@cindex warning, about missing @file{texmf.cnf}
@cindex @file{texmf.cnf} missing, warning about
If Kpathsea cannot find any @file{texmf.cnf} file, it reports a
warning including all the directories it checked.  If you don't want
to see this warning, set the environment variable
@env{KPATHSEA_WARNING} to the single character @samp{0} (zero, not
oh).

While (or instead of) reading this description, you may find it helpful
to look at the distributed @file{texmf.cnf}, which uses or at least
mentions most features.  The format of @file{texmf.cnf} files follows:

@itemize @bullet
@item
@cindex comments, in @file{texmf.cnf}
Comments start with @samp{%} and continue to the end of the line.

@item
@cindex blank lines, in @file{texmf.cnf}
Blank lines are ignored.

@item
@cindex backslash-newline
@cindex continuation character
@cindex whitespace, not ignored on continuation lines
@kindex \@r{, line continuation in @file{texmf.cnf}}
A @samp{\} at the end of a line acts as a continuation character, i.e.,
the next line is appended.  Whitespace at the beginning of continuation
lines is not ignored.

@item Each remaining line must look like

@example
@var{variable} @r{[}. @var{progname}@r{]} @r{[}=@r{]} @var{value}
@end example

@noindent where the @samp{=} and surrounding whitespace is optional.

@item
@cindex identifiers, characters valid in
The @var{variable} name may contain any character other than whitespace,
@samp{=}, or @samp{.}, but sticking to @samp{A-Za-z_} is safest.

@item If @samp{.@var{progname}} is present, the definition only
applies if the program that is running is named (i.e., the last
component of @code{argv[0]} is) @var{progname} or
@file{@var{progname}.exe}.  This allows different flavors of @TeX{} to
have different search paths, for example.

@item
@cindex right-hand side of variable assignments
@var{value} may contain any characters except @samp{%} and @samp{@@}.
(These restrictions are only necessary because of the processing done on
@file{texmf.cnf} at build time, so you can stick those characters in
after installation if you have to.)  The @samp{$@var{var}.@var{prog}}
feature is not available on the right-hand side; instead, you must use
an additional variable (see below for example).  A @samp{;} in
@var{value} is translated to @samp{:} if running under Unix; this is
useful to write a single @file{texmf.cnf} which can be used under both
Unix and NT.

@item All definitions are read before anything is expanded, so you can
use variables before they are defined (like Make, unlike most other
programs).
@end itemize

@noindent Here is a configuration file fragment illustrating most of
these points:

@example
% TeX input files -- i.e., anything to be found by \input or \openin ...
latex209_inputs = .:$TEXMF/tex/latex209//:$TEXMF/tex//
latex2e_inputs = .:$TEXMF/tex/latex//:$TEXMF/tex//
TEXINPUTS = .:$TEXMF/tex//
TEXINPUTS.latex209 = $latex209_inputs
TEXINPUTS.latex2e = $latex2e_inputs
TEXINPUTS.latex = $latex2e_inputs
@end example

@cindex shell scripts as configuration files
@cindex configuration files as shell scripts.
Although this format has obvious similarities to Bourne shell
scripts---change the comment character to @code{#}, disallow spaces
around the @code{=}, and get rid of the @code{.@var{name}} convention,
and it could be run through the shell.  But there seemed little
advantage to doing this, since all the information would have to passed
back to Kpathsea and parsed there anyway, since the @code{sh} process
couldn't affect its parent's environment.

@flindex cnf.c
The implementation of all this is in @file{kpathsea/cnf.c}.


@node Path expansion
@section Path expansion

@cindex path expansion
@cindex expansion, search path

Kpathsea recognizes certain special characters and constructions in
search paths, similar to that in shells.  As a general example:
@samp{~$USER/@{foo,bar@}//baz} expands to all subdirectories under
directories @file{foo} and @file{bar} in @t{$USER}'s home directory that
contain a directory or file @file{baz}.  These expansions are explained
in the sections below.

@menu
* Default expansion::           a: or :a or a::b expands to a default.
* Variable expansion::          $foo and $@{foo@} expand to environment values.
* Tilde expansion::             ~ and ~user expand to home directories.
* Brace expansion::             a@{foo,bar@}b expands to afoob abarb.
* KPSE_DOT expansion::          . is replaced with $KPSE_DOT if it is defined.
* Subdirectory expansion::      a// and a//b recursively expand to subdirs.
@end menu


@node Default expansion
@subsection Default expansion

@kindex :: @r{expansion}
@cindex doubled colons
@cindex leading colons
@cindex trailing colons
@cindex extra colons
@cindex default expansion
@cindex expansion, default

If the highest-priority search path (@pxref{Path sources}) contains an
@dfn{extra colon} (i.e., leading, trailing, or doubled), Kpathsea
inserts at that point the next-highest-priority search path that is
defined.  If that inserted path has an extra colon, the same happens
with the next-highest.  (An extra colon in the compile-time default
value has unpredictable results, so installers beware.)

For example, given an environment variable setting

@example
setenv TEXINPUTS /home/karl:
@end example

@noindent and a @code{TEXINPUTS} value from @file{texmf.cnf} of

@example
.:$TEXMF//tex
@end example

@noindent then the final value used for searching will be:

@example
/home/karl:.:$TEXMF//tex
@end example

Put another way, default expansion works on ``formats'' (search
paths), and not directly on environment variables.  Example, showing
the trailing @samp{:} ignored in the first case and expanded in the second:

@example
$ env TTFONTS=/tmp: kpsewhich --expand-path '$TTFONTS'
/tmp
$ env TTFONTS=/tmp: kpsewhich --show-path=.ttf
/tmp:.:/home/olaf/texmf/fonts/truetype//:...
@end example

Since Kpathsea looks for multiple configuration files, it would be
natural to expect that (for example) an extra colon in
@file{./texmf.cnf} would expand to the path in @file{$TEXMF/texmf.cnf}.
Or, with Dvips' configuration files, that an extra colon in
@file{config.$PRINTER} would expand to the path in @file{config.ps}.
This doesn't happen.  It's not clear this would be desirable in all
cases, and trying to devise a way to specify the path to which the extra
colon should expand seemed truly baroque.
@cindex Bach, Johann Sebastian

Technicality: Since it would be useless to insert the default value in
more than one place, Kpathsea changes only one extra @samp{:} and leaves
any others in place (they will eventually be ignored).  Kpathsea checks
first for a leading @samp{:}, then a trailing @samp{:}, then a doubled
@samp{:}.

@flindex kdefault.c
You can trace this by debugging ``paths'' (@pxref{Debugging}).
Default expansion is implemented in the source file
@file{kpathsea/kdefault.c}.


@node Variable expansion
@subsection Variable expansion

@kindex $ @r{expansion}
@cindex environment variables in paths
@cindex variable expansion
@cindex expansion, variable
@flindex texmf.cnf@r{, and variable expansion}

@samp{$foo} or @samp{$@{foo@}} in a path element is replaced by (1) the
value of an environment variable @samp{foo} (if defined); (2) the value
of @samp{foo} from @file{texmf.cnf} (if defined); (3) the empty string.

If the character after the @samp{$} is alphanumeric or @samp{_}, the
variable name consists of all consecutive such characters. If the
character after the @samp{$} is a @samp{@{}, the variable name consists
of everything up to the next @samp{@}} (braces may not be nested around
variable names).  Otherwise, Kpathsea gives a warning and ignores the
@samp{$} and its following character.

@cindex quoting variable values
@cindex shell variables
You must quote the @t{$}'s and braces as necessary for your shell.
@emph{Shell} variable values cannot be seen by Kpathsea, i.e., ones
defined by @code{set} in C shells and without @code{export} in Bourne
shells.

For example, given
@example
setenv tex /home/texmf
setenv TEXINPUTS .:$tex:$@{tex@}prev
@end example
@noindent the final @code{TEXINPUTS} path is the three directories:
@example
.:/home/texmf:/home/texmfprev
@end example

The @samp{.@var{progname}} suffix on variables and
@samp{_@var{progname}} on environment variable names are not implemented
for general variable expansions.  These are only recognized when search
paths are initialized (@pxref{Path sources}).

@flindex variable.c
Variable expansion is implemented in the source file
@file{kpathsea/variable.c}.


@node Tilde expansion
@subsection Tilde expansion

@kindex ~ @r{expansion}
@cindex home directories in paths
@cindex tilde expansion
@cindex expansion, tilde

@vindex HOME@r{, as ~ expansion}
@vindex USERPROFILE@r{, as ~ expansion}
A leading @samp{~} in a path element is replaced by the value of the
environment variable @code{HOME}, or @file{.} if @code{HOME} is not
set.  On Windows, the environment variable @code{USERPROFILE} is
checked instead of @code{HOME}.

A leading @samp{~@var{user}} in a path element is replaced by
@var{user}'s home directory from the system @file{passwd} database.

For example,
@example
setenv TEXINPUTS ~/mymacros:
@end example

@noindent will prepend a directory @file{mymacros} in your home
directory to the default path.

@cindex @t{root} user
@cindex trailing @samp{/} in home directory
@kindex /@r{, trailing in home directory}
As a special case, if a home directory ends in @samp{/}, the trailing
slash is dropped, to avoid inadvertently creating a @samp{//} construct
in the path.  For example, if the home directory of the user @samp{root}
is @samp{/}, the path element @samp{~root/mymacros} expands to just
@samp{/mymacros}, not @samp{//mymacros}.

@flindex tilde.c
Tilde expansion is implemented in the source file @file{kpathsea/tilde.c}.


@node Brace expansion
@subsection Brace expansion

@kindex @{ @r{expansion}
@cindex brace expansion

@samp{x@{@var{a},@var{b}@}y} expands to @samp{x@var{a}y:x@var{b}y}.
For example:

@example
foo/@{1,2@}/baz
@end example

@noindent expands to @samp{foo/1/baz:foo/2/baz}.  @samp{:} is the path
separator on the current system; e.g., on a DOS system, it's @samp{;}.

Braces can be nested; for example, @samp{x@{A,B@{1,2@}@}y} expands to
@samp{xAy:xB1y:xB2y}.

Multiple non-nested braces are expanded from right to left; for example,
@samp{x@{A,B@}@{1,2@}y} expands to @samp{x@{A,B@}1y:x@{A,B@}2y}, which
expands to @samp{xA1y:xB1y:xA2y:xB2y}.

@cindex multiple @TeX{} hierarchies
This feature can be used to implement multiple @TeX{} hierarchies, by
assigning a brace list to @code{$TEXMF}, as mentioned in
@file{texmf.in}.

You can also use the path separator in stead of the comma.  The last
example could have been written @samp{x@{A:B@}@{1:2@}y}.


@flindex expand.c
Brace expansion is implemented in the source file
@file{kpathsea/expand.c}.  It is a modification of the Bash sources, and
is thus covered by the GNU General Public License, rather than the
Library General Public License that covers the rest of Kpathsea.


@node KPSE_DOT expansion
@subsection @code{KPSE_DOT} expansion

@kindex KPSE_DOT @r{expansion}

When @code{KPSE_DOT} is defined in the environment, it names a directory
that should be considered the current directory for the purpose of
looking up files in the search paths.  This feature is needed by the
@samp{mktex@dots{}} scripts @ref{mktex scripts}, because these
change the working directory.  You should not ever define it yourself.


@node Subdirectory expansion
@subsection Subdirectory expansion

@kindex //
@cindex subdirectory searching
@cindex expansion, subdirectory

@cindex alphabetical order, not
Two or more consecutive slashes in a path element following a directory
@var{d} is replaced by all subdirectories of @var{d}: first those
subdirectories directly under @var{d}, then the subsubdirectories under
those, and so on.  At each level, the order in which the directories are
searched is unspecified.  (It's ``directory order'', and definitely not
alphabetical.)

If you specify any filename components after the @samp{//}, only
subdirectories which match those components are included.  For example,
@samp{/a//b} would expand into directories @file{/a/1/b}, @file{/a/2/b},
@file{/a/1/1/b}, and so on, but not @file{/a/b/c} or @file{/a/1}.

You can include multiple @samp{//} constructs in the path.

@samp{//} at the beginning of a path is ignored; you didn't really want
to search every directory on the system, did you?

@cindex trick for detecting leaf directories
@cindex leaf directory trick
@cindex Farwell, Matthew
@cindex MacKenzie, David
I should mention one related implementation trick, which I took from GNU
find.  Matthew Farwell suggested it, and David MacKenzie implemented it.

@vindex st_nlink
The trick is that in every real Unix implementation (as opposed to the
POSIX specification), a directory which contains no subdirectories will
have exactly two links (namely, one for @file{.} and one for @file{..}).
That is to say, the @code{st_nlink} field in the @samp{stat} structure
will be two.  Thus, we don't have to stat everything in the bottom-level
(leaf) directories---we can just check @code{st_nlink}, notice it's two,
and do no more work.

But if you have a directory that contains a single subdirectory and 500
regular files, @code{st_nlink} will be 3, and Kpathsea has to stat every
one of those 501 entries.  Therein lies slowness.

@vindex ST_NLINK_TRICK
You can disable the trick by undefining @code{ST_NLINK_TRICK} in
@file{kpathsea/config.h}. (It is undefined by default except under Unix.)

@flindex elt-dirs.c
Unfortunately, in some cases files in leaf directories are
@code{stat}'d: if the path specification is, say,
@samp{$TEXMF/fonts//pk//}, then files in a subdirectory
@samp{@dots{}/pk}, even if it is a leaf, are checked. The reason cannot
be explained without reference to the implementation, so read
@file{kpathsea/elt-dirs.c} (search for @samp{may descend}) if you are
curious.  And if you can find a way to @emph{solve} the problem, please
let me know.

@flindex elt-dirs.c
Subdirectory expansion is implemented in the source file
@file{kpathsea/elt-dirs.c}.


@node Filename database
@section Filename database (@code{ls-R})

@cindex filename database
@cindex database, for filenames
@cindex externally-built filename database

Kpathsea goes to some lengths to minimize disk accesses for searches
(@pxref{Subdirectory expansion}).  Nevertheless, in practice searching
each possible directory in typical @TeX{} installations takes an
excessively long time.

Therefore, Kpathsea can use an externally-built @dfn{filename
database} file named @file{ls-R} that maps files to directories, thus
avoiding the need to exhaustively search the disk.

A second database file @file{aliases} allows you to give additional
names to the files listed in @file{ls-R}.  This can be helpful to adapt
to ``8.3'' filename conventions in source files.

The @file{ls-R} and @file{aliases} features are implemented in the
source file @file{kpathsea/db.c}.

@menu
* ls-R::                        The main filename database.
* Filename aliases::            Aliases for those names.
* Database format::             Syntax details of the database file.
@end menu


@node ls-R
@subsection @file{ls-R}

@flindex ls-R @r{database file}
@vindex TEXMFDBS

As mentioned above, you must name the main filename database
@file{ls-R}.  You can put one at the root of each @TeX{} installation
hierarchy you wish to search (@code{$TEXMF} by default); most sites have
only one hierarchy.  Kpathsea looks for @file{ls-R} files along the
@code{TEXMFDBS} path, so that should presumably match the list of
hierarchies.

The recommended way to create and maintain @samp{ls-R} is to run the
@code{mktexlsr} script, which is installed in @samp{$(bindir)}
(@file{/usr/local/bin} by default).  That script goes to some trouble to
follow symbolic links as necessary, etc.  It's also invoked by the
distributed @samp{mktex@dots{}} scripts.

@flindex ls-R@r{, simplest build}
At its simplest, though, you can build @file{ls-R} with the command
@example
cd @var{/your/texmf/root} && ls -LAR ./ >ls-R
@end example

@noindent
@opindex --color=tty
@flindex /etc/profile @r{and aliases}
presuming your @code{ls} produces the right output format (see the
section below).  GNU @code{ls}, for example, outputs in this format.
Also presuming your @code{ls} hasn't been aliased in a system file
(e.g., @file{/etc/profile}) to something problematic, e.g., @samp{ls
--color=tty}.  In that case, you will have to disable the alias before
generating @file{ls-R}.  For the precise definition of the file format,
see @ref{Database format}.

Regardless of whether you use the supplied script or your own, you will
almost certainly want to invoke it via @code{cron}, so when you make
changes in the installed files (say if you install a new La@TeX{}
package), @file{ls-R} will be automatically updated.

@opindex -A @r{option to @code{ls}}
@cindex dot files
@flindex . @r{files}
@flindex . @r{directories, ignored}
@flindex .tex @r{file, included in @file{ls-R}}
The @samp{-A} option to @code{ls} includes files beginning with @samp{.}
(except for @file{.} and @file{..}), such as the file @file{.tex}
included with the La@TeX{} tools package.  (On the other hand,
@emph{directories} whose names begin with @samp{.} are always ignored.)

@cindex symbolic links, and @file{ls-R}
@opindex -L @r{option to @code{ls}}
If your system does not support symbolic links, omit the @samp{-L}.

@cindex automounter, and @file{ls-R}
@cindex NFS and @file{ls-R}
@code{ls -LAR @var{/your/texmf/root}} will also work.  But using
@samp{./} avoids embedding absolute pathnames, so the hierarchy can be
easily transported.  It also avoids possible trouble with automounters
or other network filesystem conventions.

@cindex warning about unusable @file{ls-R}
@cindex unusable @file{ls-R} warning
Kpathsea warns you if it finds an @file{ls-R} file, but the file does
not contain any usable entries.  The usual culprit is running plain
@samp{ls -R} instead of @samp{ls -LR ./} or @samp{ls -R
@var{/your/texmf/root}}.  Another possibility is some system directory
name starting with a @samp{.} (perhaps if you are using AFS); Kpathsea
ignores everything under such directories.

@kindex !! @r{in path specifications}
@cindex disk searching, avoiding
Because the database may be out-of-date for a particular run, if a file
is not found in the database, by default Kpathsea goes ahead and
searches the disk. If a particular path element begins with @samp{!!},
however, @emph{only} the database will be searched for that element,
never the disk.  If the database does not exist, nothing will be
searched.  Because this can surprise users (``I see the font
@file{foo.tfm} when I do an @code{ls}; why can't Dvips find it?''), it
is not in any of the default search paths.


@node Filename aliases
@subsection Filename aliases

@cindex filename aliases
@cindex aliases, for filenames

In some circumstances, you may wish to find a file under several names.
For example, suppose a @TeX{} document was created using a DOS system
and tries to read @file{longtabl.sty}.  But now it's being run on a Unix
system, and the file has its original name, @file{longtable.sty}.  The
file won't be found.  You need to give the actual file
@file{longtable.sty} an alias @samp{longtabl.sty}.

@c As another example, suppose you are creating a @TeX{} distribution on a
@c CD-ROM or a DOS system; then the file @file{mf.base} gets stored as
@c @file{mf.bas}.  But Metafont on Unix wants to find @file{mf.base}.  Here
@c you need to give the actual file @file{mf.bas} an alias @samp{mf.base}.

You can handle this by creating a file @file{aliases} as a companion to
the @file{ls-R} for the hierarchy containing the file in question.  (You
must have an @file{ls-R} for the alias feature to work.)

The format of @file{aliases} is simple: two whitespace-separated words
per line; the first is the real name @file{longtable.sty}, and second is
the alias (@file{longtabl.sty}).  These must be base filenames, with no
directory components.  @file{longtable.sty} must be in the sibling
@file{ls-R}.

Also, blank lines and lines starting with @samp{%} or @samp{#} are
ignored in @file{aliases}, to allow for comments.

If a real file @file{longtabl.sty} exists, it is used regardless of any
aliases.


@node Database format
@subsection Database format

@cindex format of external database
@cindex database, format of

The ``database'' read by Kpathsea is a line-oriented file of plain
text. The format is that generated by GNU (and most other) @code{ls}
programs given the @samp{-R} option, as follows.

@itemize @bullet
@item
Blank lines are ignored.

@item
If a line begins with @samp{/} or @samp{./} or @samp{../} and ends with
a colon, it's the name of a directory.  (@samp{../} lines aren't useful,
however, and should not be generated.)

@item
All other lines define entries in the most recently seen directory.
@t{/}'s in such lines will produce possibly-strange results.

@item
Files with no preceding directory line are ignored.
@end itemize

For example, here's the first few lines of @file{ls-R} (which totals
about 30K bytes) on my system:

@example
bibtex
dvips
fonts
ls-R
metafont
metapost
tex
web2c

./bibtex:
bib
bst
doc

./bibtex/bib:
asi.bib
btxdoc.bib
@dots{}
@end example


@node Invoking kpsewhich
@section @code{kpsewhich}: Standalone path searching

@pindex kpsewhich
@cindex path searching, standalone
@cindex standalone path searching

The Kpsewhich program exercises the path searching functionality
independent of any particular application.  This can also be useful as a
sort of @code{find} program to locate files in your @TeX{} hierarchies,
perhaps in administrative scripts.  It is used heavily in the
distributed @samp{mktex@dots{}} scripts.

Synopsis:

@example
kpsewhich @var{option}@dots{} @var{filename}@dots{}
@end example

The options and filename(s) to look up can be intermixed.
Options can start with either @samp{-} or @samp{--}, and any unambiguous
abbreviation is accepted.

@menu
* Path searching options::      Changing the mode, resolution, etc.
* Specially-recognized files::  Default formats for texmf.cnf, etc.
* Auxiliary tasks::             Path and variable expansion.
* Standard options::            --help and --version.
@end menu


@node Path searching options
@subsection Path searching options

@cindex path searching options

Kpsewhich looks up each non-option argument on the command line as a
filename, and returns the first file found.

Various options alter the path searching behavior:

@table @samp
@item --all
@opindex --all
@cindex all matches, finding
Report all matches found, one per line.  By default, if there is more
than one match, just one will be reported (chosen effectively at random).

@item --dpi=@var{num}
@opindex --dpi=@var{num}
@opindex -D @var{num}
@cindex resolution, setting
Set the resolution to @var{num}; this only affects @samp{gf} and
@samp{pk} lookups.  @samp{-D} is a synonym, for compatibility with
Dvips.  Default is 600.

@item --engine=@var{name}
@opindex --engine=@var{name}
@cindex engine name
Set the engine name to @var{name}.  By default it is not set.  The
engine name is used in some search paths to allow files with the same
name but used by different engines to coexist.

In particular, since the memory dump files
(@file{.fmt}/@file{.base}/@file{.mem}) are now stored in
subdirectories named for the engine (@file{tex}, @file{pdftex},
@file{xetex}, etc.), you must specify an engine name in order to find
them.  For example, @file{cont-en.fmt} typically exists for both
@file{pdftex} and @file{xetex}.  With the default path settings, you
can use @samp{--engine=/} to look for any dump file, regardless of
engine; if a dump file exists for more than one engine, it's
indeterminate which one is returned.  (The @samp{/} ends up specifying
a normal recursive search along the path where the dumps are stored,
namely @samp{$TEXMF/web2c@{/$engine,@}}.)

@item --format=@var{name}
@opindex --format=@var{name}
Set the format for lookup to @var{name}.  By default, the format is
guessed from the filename, with @samp{tex} being used if nothing else
fits.  The recognized filename extensions (including any leading
@samp{.}) are also allowable @var{name}s.

All formats also have a name, which is the only way to specify formats
with no associated suffix.  For example, for Dvips configuration files
you can use @samp{--format="dvips config"}.  (The quotes are for the
sake of the shell.)

Here's the current list of recognized names and the associated suffixes.
@xref{Supported file formats}, for more information on each of these.

The strings in parentheses are abbreviations recognized only by
@code{kpsewhich} (not the underlying library calls).  They are
provided when it would otherwise require an argument containing a
space to specify the format, to simplify quoting of calls from shells.

@example
gf: gf
pk: pk
bitmap font (bitmapfont):
tfm: .tfm
afm: .afm
base: .base
bib: .bib
bst: .bst
cnf: .cnf
ls-R: ls-R ls-r
fmt: .fmt
map: .map
mem: .mem
mf: .mf
mfpool: .pool
mft: .mft
mp: .mp
mppool: .pool
MetaPost support (mpsupport):
ocp: .ocp
ofm: .ofm .tfm
opl: .opl  .pl
otp: .otp
ovf: .ovf .vf
ovp: .ovp  .vpl
graphic/figure:  .eps .epsi
tex: .tex  .sty .cls .fd .aux .bbl .def .clo .ldf
TeX system documentation (doc):
texpool: .pool
TeX system sources (source):  .dtx .ins
PostScript header:  .pro
Troff fonts (trofffont):
type1 fonts: .pfa .pfb
vf: .vf
dvips config (dvipsconfig):
ist: .ist
truetype fonts: .ttf .ttc .TTF .TTC
type42 fonts: .t42 .T42
web2c files (web2c):
other text files (othertext):
other binary files (otherbin):
misc fonts (miscfont):
web: .web  .ch
cweb: .w .web  .ch
enc files: .enc
cmap files (cmap):
subfont definition files: .sfd
opentype fonts: .otf
pdftex config (pdftexconfig):
lig files: .lig
texmfscripts:
lua: .luc .luctex .texluc .lua .luatex .texlua
font feature files: .fea
cid maps: .cid .cidmap
mlbib: .mlbib .bib
mlbst: .mlbst .bst
clua: .dll .so
@end example

This option and @samp{--path} are mutually exclusive.

@item --interactive
@opindex --interactive
@cindex interactive query
After processing the command line, read additional filenames to look up
from standard input.

@item --mktex=@var{filetype}
@itemx --no-mktex=@var{filetype}
@opindex --mktex=@var{filetype}
@opindex --no-mktex=@var{filetype}
Turn on or off the @samp{mktex} script associated with @var{filetype}.
Usual values for @var{filetype} are @samp{pk}, @samp{mf}, @samp{tex},
and @samp{tfm}.  By default, all are off in Kpsewhich, even if they
are enabled for @TeX{}.  This option implies setting
@code{--must-exist}.  @xref{mktex scripts}.

@item --mode=@var{string}
@opindex --mode=@var{string}
Set the mode name to @var{string}; this also only affects @samp{gf} and
@samp{pk} lookups.  No default: any mode will be found.  @xref{mktex
script arguments}.

@item --must-exist
@opindex --must-exist
Do everything possible to find the files, notably including searching
the disk and running the @samp{mktex} scripts.  By default, only the
@file{ls-R} database is checked, in the interest of efficiency.

@item --path=@var{string}
@opindex --path=@var{string}
Search along the path @var{string} (colon-separated as usual), instead
of guessing the search path from the filename.  @samp{//} and all the
usual expansions are supported (@pxref{Path expansion}).  This option
and @samp{--format} are mutually exclusive.  To output the complete
directory expansion of a path, instead of doing a one-shot lookup, see
@samp{--expand-path} and @samp{--show-path} in the following section.

@item --progname=@var{name}
@opindex --progname=@var{name}
Set the program name to @var{name}; default is @samp{kpsewhich}.  This
can affect the search paths via the @samp{.@var{prognam}} feature in
configuration files (@pxref{Config files}).

@item --safe-in-name=@var{name}
@itemx --safe-out-name=@var{name}
@opindex --safe-in-name=@var{name}
@opindex --safe-out-name=@var{name}
Exit successfully if @var{name} is safe to open for reading or
writing, respectively, else unsuccessfully.  No output is written.
These tests take account of the related Kpathsea configuration
settings (@pxref{Calling sequence}).

@item --subdir=@var{string}
@opindex --subdir=@var{string}
Report only those matches whose directory part @emph{ends} with
@var{string} (compared literally, except case is ignored on a
case-insensitive operating system).  For example, suppose there are
two matches for a given name:

@example
kpsewhich foo.sty
@result{} /some/where/foo.sty
/another/place/foo.sty
@end example

@noindent
Then we can narrow the result to what we are interested in with
@option{--subdir}:

@example
kpsewhich --subdir=where foo.sty
@result{} /some/where/foo.sty

kpsewhich --subdir=place foo.sty
@result{} /another/place/foo.sty
@end example

@noindent
The string to match must be at the end of the directory part of the
match, and it is taken literally, with no pattern matching:

@example
kpsewhich --subdir=another foo.sty
@result{}
@end example

@noindent
The string to match may cross directory components:

@example
kpsewhich --subdir=some/where foo.sty
@result{} /some/where/foo.sty
@end example

@noindent
@option{--subdir} implies @option{--all}; if there is more than one
match, they will all be reported (in our example, both @samp{where}
and @samp{place} end in @samp{e}):

@example
kpsewhich --subdir=e
@result{} /some/where/foo.sty
/another/place/foo.sty
@end example

@noindent
Because of the above rules, the presence of a leading @samp{/} is
important, since it ``anchors'' the match to a full component name:

@example
kpsewhich --subdir=/lace foo.sty
@result{}
@end example

@noindent
However, a trailing @samp{/} is immaterial (and ignored), since the
match always takes place at the end of the directory part:

@example
kpsewhich --subdir=lace/ foo.sty
@result{} /another/place/foo.sty
@end example

@noindent
The purpose of these rules is to make it convenient to find results
only within a particular area of the tree.  For instance, a given
script named @file{foo.lua} might exist within both
@file{texmf-dist/scripts/pkg1/} and @file{texmf-dist/scripts/pkg2/}.
By specifying, say, @samp{--subdir=/pkg1}, you can be sure of getting
the one you are interested in.

We only match at the end because a site might happen to install @TeX{}
in @file{/some/coincidental/pkg1/path/}, and we wouldn't want to match
@file{texmf-dist/scripts/pkg2/} that when searching for @samp{/pkg1}.

@end table


@node Specially-recognized files
@subsection Specially-recognized files for @command{kpsewhich}

@command{kpsewhich} recognizes a few special filenames on the command
line and defaults to using the `known' file formats for them, merely
to save the time and trouble of specifying the format.  This is only a
feature of @command{kpsewhich}; when using the Kpathsea library
itself, none of these special filenames are recognized, and it's still
up to the caller to specify the desired format.

Here is the list of special filenames to @command{kpsewhich}, along
with their corresponding format:

@table @file

@flindex config.ps
@item config.ps
@code{dvips config}

@flindex dvipdfmx.cfg
@item dvipdfmx.cfg
@samp{other text files}

@flindex fmtutil.cnf
@item fmtutil.cnf
@samp{web2c files}

@flindex glyphlist.txt
@item glyphlist.txt
@samp{map}

@flindex mktex.cnf
@item mktex.cnf
@samp{web2c files}

@flindex pdfglyphlist.txt
@item pdfglyphlist.txt
@samp{map}

@flindex pdftex.cfg
@flindex pdftexconfig.tex
@item pdftex.cfg
@samp{pdftex config} (although @file{pdftex.cfg} is not used any more;
look for the file @file{pdftexconfig.tex} instead.)

@flindex texmf.cnf
@item texmf.cnf
@samp{cnf}

@flindex XDvi
@item XDvi
@samp{other text files}

@end table

A user-specified format will override the above defaults.

@flindex tcfmgr.map
Another useful configuration file in this regard is @file{tcfmgr.map},
found in @file{texmf/texconfig/tcfmgr.map}, which records various
information about the above configuration files (among others).


@node Auxiliary tasks
@subsection Auxiliary tasks

@cindex auxiliary tasks

Kpsewhich provides some additional features not strictly related to path
lookup:

@itemize @bullet
@item
@opindex --debug=@var{num}
@samp{--debug=@var{num}} sets the debugging options to @var{num}.
@xref{Debugging}.

@item
@opindex --var-value=@var{variable}
@samp{--var-value=@var{variable}} outputs the value of @var{variable},
expanding @samp{$} (@pxref{Variable expansion} and @samp{~} (@pxref{Tilde
expansion}) constructs, but not performing other expansions.

@item
@opindex --expand-braces=@var{string}
@samp{--expand-braces=@var{string}} outputs the variable and brace
expansion of @var{string}.  @xref{Path expansion}.

@item
@opindex --expand-var=@var{string}
@samp{--expand-var=@var{string}} outputs the variable and tilde
expansion of @var{string}.  For example, the @samp{mktex@dots{}}
scripts run @samp{kpsewhich --expand-var='$TEXMF'} to find the root of
the @TeX{} system hierarchy.  @xref{Path expansion}.

@item
@opindex --expand-path=@var{string}
@samp{--expand-path=@var{string}} outputs the complete expansion of
@var{string}, with each element separated by the usual path separator
on the current system (@samp{;} on Windows, @samp{:} otherwise).
This may be useful to construct a custom search path for a format not
otherwise supported.  To retrieve the search path for a format that is
already supported, see @samp{--show-path}, next.

Nonexistent directories are culled from the output:

@example
$ kpsewhich --expand-path '/tmp'
@result{} /tmp
$ kpsewhich --expand-path '/nonesuch'
@result{}
@end example

For one-shot uses of an arbitrary (not built in to Kpathsea) path, see
@samp{--path} in the previous section.

@item
@opindex --show-path=@var{name}
@samp{--show-path=@var{name}} shows the path that would be used for file
lookups of file type @var{name}.  Either a filename extension
(@samp{pk}, @samp{.vf}, etc.) or an integer can be used, just as with
@samp{--format}, described in the previous section.

@end itemize


@node Standard options
@subsection Standard options

@cindex standard options

Kpsewhich accepts the standard GNU options:

@itemize @bullet
@item
@opindex --help
@samp{--help} prints a help message on standard output and exits
successfully.

@item
@opindex --version
@samp{--version} prints the Kpathsea version number and exits successfully.
@end itemize


@node TeX support
@chapter @TeX{} support

@cindex @TeX{} support

Although the basic features in Kpathsea can be used for any type of path
searching, it came about (like all libraries) with a specific
application in mind: I wrote Kpathsea specifically for @TeX{} system
programs.  I had been struggling with the programs I was using (Dvips,
Xdvi, and @TeX{} itself) having slightly different notions of how to
specify paths; and debugging was painful, since no code was shared.

Therefore, Kpathsea provides some @TeX{}-specific formats and features.
Indeed, many of the supposedly generic path searching features were
provided because they seemed useful in that con@TeX{}t (font lookup,
particularly).

Kpathsea provides a standard way to search for files of any of the
supported file types; glyph fonts are a bit different than all the rest.
Searches are based solely on filenames, not file contents---if a GF
file is named @file{cmr10.600pk}, it will be found as a PK file.

@menu
* Supported file formats::      File types Kpathsea knows about.
* File lookup::                 Searching for most kinds of files.
* Glyph lookup::                Searching for bitmap fonts.
* Suppressing warnings::        Avoiding warnings via TEX_HUSH.
@end menu


@node Supported file formats
@section Supported file formats

@cindex supported file formats
@cindex file formats, supported

@cindex environment variables for @TeX{}
@cindex @TeX{} environment variables

Kpathsea has support for a number of file types.  Each file type has a
list of environment and config file variables that are checked to define
the search path, and most have a default suffix that plays a role in
finding files (see the next section).  Some also define additional
suffixes, and/or a program to be run to create missing files on the fly.

@cindex program-varying paths
Since environment variables containing periods, such as
@samp{TEXINPUTS.latex}, are not allowed on some systems, Kpathsea looks
for environment variables with an underscore, e.g.,
@samp{TEXINPUTS_latex} (@pxref{Config files}).

The following table lists the above information.

@table @samp
@item afm
@flindex .afm
@vindex AFMFONTS
(Adobe font metrics, @pxref{Metric files,,, dvips, Dvips})
@code{AFMFONTS};
suffix @samp{.afm}.

@item base
@flindex .base
@vindex MFBASES
@vindex TEXMFINI
(Metafont memory dump, @pxref{Memory dumps,,, web2c, Web2c})
@code{MFBASES}, @code{TEXMFINI};
suffix @samp{.base}.

@item bib
@flindex .bib
@vindex BIBINPUTS
@vindex TEXBIB
(Bib@TeX{} bibliography source, @pxref{bibtex invocation,,, web2c, Web2c})
@code{BIBINPUTS}, @code{TEXBIB};
suffix @samp{.bib}.

@item bst
@flindex .bst
@vindex BSTINPUTS
(Bib@TeX{} style, @pxref{Basic BibTeX style files,, Basic Bib@TeX{}
style files, web2c, Web2c})
@code{BSTINPUTS};
suffix @samp{.bst}.

@item cmap
@flindex .cmap
@vindex CMAPFONTS
(character map files)
@code{CMAPFONTS};
suffix @samp{.cmap}.

@item cnf
@flindex .cnf
@vindex TEXMFCNF
(Runtime configuration files, @pxref{Config files})
@code{TEXMFCNF};
suffix @samp{.cnf}.

@item cweb
@flindex .w
@flindex .web
@vindex CWEBINPUTS
(CWEB input files)
@code{CWEBINPUTS};
suffixes @samp{.w}, @samp{.web};
additional suffix @samp{.ch}.

@item dvips config
@vindex TEXCONFIG
@flindex config.ps@r{, search path for}
(Dvips @samp{config.*} files, such as @file{config.ps}, @pxref{Config
files,,, dvips, Dvips})
@code{TEXCONFIG}.

@item enc files
@flindex .enc
@vindex ENCFONTS
(encoding vectors)
@code{ENCFONTS};
suffix @samp{.enc}.

@item fmt
@flindex .fmt
@vindex TEXFORMATS
@vindex TEXMFINI
(@TeX{} memory dump, @pxref{Memory dumps,,, web2c, Web2c})
@code{TEXFORMATS}, @code{TEXMFINI};
suffix @samp{.fmt}.

@item font cid map
@flindex .cid
@vindex FONTCIDMAPS
(CJK mapping)
@code{FONTCIDMAPS}
suffix @samp{.cid}.

@item font feature files
@flindex .fea
@vindex FONTFEATURES
(primarily for OpenType font features)
@code{FONTFEATURES}
suffix @samp{.fea}.

@item gf
@flindex gf
@vindex GFFONTS
@vindex GLYPHFONTS
@vindex TEXFONTS
(generic font bitmap, @pxref{Glyph files,,, dvips, Dvips})
@code{@var{program}FONTS}, @code{GFFONTS}, @code{GLYPHFONTS}, @code{TEXFONTS};
suffix @samp{gf}.

@item graphic/figure
@flindex .eps
@flindex .epsi
@vindex TEXPICTS
@vindex TEXINPUTS
(Encapsulated PostScript figures, @pxref{PostScript figures,,, dvips, Dvips})
@code{TEXPICTS}, @code{TEXINPUTS};
additional suffixes: @samp{.eps}, @samp{.epsi}.

@item ist
@flindex .ist
@vindex TEXINDEXSTYLE
@vindex INDEXSTYLE
(makeindex style files)
@code{TEXINDEXSTYLE}, @code{INDEXSTYLE};
suffix @samp{.ist}.

@item lig files
@flindex .lig
@vindex LIGFONTS
(ligature definition files)
@code{LIGFONTS};
suffix @samp{.lig}.

@item ls-R
@flindex ls-R
@vindex TEXMFDBS
(Filename databases, @pxref{Filename database})
@code{TEXMFDBS}.

@item map
@flindex .map
@vindex TEXFONTMAPS
(Fontmaps, @pxref{Fontmap})
@code{TEXFONTMAPS};
suffix @samp{.map}.

@item mem
@flindex .mem
@vindex MPMEMS
@vindex TEXMFINI
(MetaPost memory dump, @pxref{Memory dumps,,, web2c, Web2c})
@code{MPMEMS}, @code{TEXMFINI};
suffix @samp{.mem}.

@item @r{MetaPost support}
@vindex MPSUPPORT
(MetaPost support files, used by DMP; @pxref{dmp invocation,,, web2c, Web2c})
@code{MPSUPPORT}.

@item mf
@flindex .mf
@vindex MFINPUTS
(Metafont source, @pxref{mf invocation,,, web2c, Web2c})
@code{MFINPUTS};
suffix @samp{.mf};
dynamic creation program: @code{mktexmf}.

@item mfpool
@flindex .pool
@vindex MFPOOL
(Metafont program strings, @pxref{pooltype invocation,,, web2c, Web2c})
@code{MFPOOL}, @code{TEXMFINI};
suffix @samp{.pool}.

@item mft
@flindex .mft
@vindex MFTINPUTS
(@code{MFT} style file, @pxref{mft invocation,,, web2c, Web2c})
@code{MFTINPUTS};
suffix @samp{.mft}.

@item misc fonts
@vindex MISCFONTS
(font-related files that don't fit the other categories)
@code{MISCFONTS}

@item mlbib
@flindex .mlbib
@vindex MLBIBINPUTS
@vindex BIBINPUTS
@vindex TEXBIB
(MlBib@TeX{} bibliography source)
@code{MLBIBINPUTS}, @code{BIBINPUTS}, @code{TEXBIB};
suffixes @samp{.mlbib}, @samp{.mlbib}.

@item mlbst
@flindex .mlbst
@vindex MLBSTINPUTS
@vindex BSTINPUTS
(MlBib@TeX{} style)
@code{MLBSTINPUTS}, @code{BSTINPUTS};
suffixes @samp{.mlbst}, @samp{.bst}.

@item mp
@flindex .mp
@vindex MPINPUTS
(MetaPost source, @pxref{mpost invocation,,, web2c, Web2c})
@code{MPINPUTS};
suffix @samp{.mp}.

@item mppool
@flindex .pool
@vindex MPPOOL
(MetaPost program strings, @pxref{pooltype invocation,,, web2c, Web2c})
@code{MPPOOL}, @code{TEXMFINI};
suffix @samp{.pool}.

@item ocp
@flindex .ocp
@vindex OCPINPUTS
(Omega compiled process files)
@code{OCPINPUTS}; @*
suffix @samp{.ocp};
dynamic creation program: @code{MakeOmegaOCP}.

@item ofm
@flindex .ofm
@vindex OFMFONTS
(Omega font metrics)
@code{OFMFONTS}, @code{TEXFONTS}; @*
suffixes @samp{.ofm}, @samp{.tfm};
dynamic creation program: @code{MakeOmegaOFM}.

@item opentype fonts
@vindex OPENTYPEFONTS
(OpenType fonts)
@code{OPENTYPEFONTS}.

@item opl
@flindex .opl
(Omega property lists)
@code{OPLFONTS}, @code{TEXFONTS};
suffix @samp{.opl}.

@item otp
@flindex .otp
@vindex OTPINPUTS
(Omega translation process files)
@code{OTPINPUTS};
suffix @samp{.otp}.

@item ovf
@flindex .ovf
@vindex OVFFONTS
(Omega virtual fonts)
@code{OVFFONTS}, @code{TEXFONTS};
suffix @samp{.ovf}.

@item ovp
@flindex .ovp
@vindex OVPFONTS
(Omega virtual property lists)
@code{OVPFONTS}, @code{TEXFONTS};
suffix @samp{.ovp}.

@item pdftex config
@vindex PDFTEXCONFIG
(PDF@TeX{}-specific configuration files)
@code{PDFTEXCONFIG}.

@item pk
@flindex .pk
@vindex PKFONTS
@vindex TEXPKS
@vindex GLYPHFONTS
@vindex TEXFONTS
(packed bitmap fonts, @pxref{Glyph files,,, dvips, Dvips})
@code{@var{PROGRAM}FONTS} (@var{program} being @samp{XDVI}, etc.),
@code{PKFONTS}, @code{TEXPKS}, @code{GLYPHFONTS}, @code{TEXFONTS};
suffix @samp{pk};
dynamic creation program: @code{mktexpk}.

@item PostScript header
@flindex .pro
@vindex TEXPSHEADERS
@vindex PSHEADERS
(downloadable PostScript, @pxref{Header files,,, dvips, Dvips})
@code{TEXPSHEADERS}, @code{PSHEADERS};
additional suffix @samp{.pro}.

@item subfont definition files
@flindex .sfd
@vindex SFDFONTS
(subfont definition files)
@code{SFDFONTS}
suffix @samp{.sfd}.

@item tex
@flindex .tex
@vindex TEXINPUTS
(@TeX{} source, @pxref{tex invocation,,, web2c, Web2c})
@code{TEXINPUTS};
suffix @samp{.tex};
additional suffixes: none, because such a list cannot be complete;
dynamic creation program: @code{mktextex}.

@item TeX system documentation
@flindex doc files
@vindex TEXDOCS
(Documentation files for the @TeX{} system)
@code{TEXDOCS}.

@item TeX system sources
@flindex source files
@vindex TEXSOURCES
(Source files for the @TeX{} system)
@code{TEXSOURCES}.

@item texmfscripts
@vindex TEXMFSCRIPTS
(Architecture-independent executables distributed in the texmf trees)
@code{TEXMFSCRIPTS}.

@item texpool
@flindex .pool
@vindex TEXPOOL
(@TeX{} program strings, @pxref{pooltype invocation,,, web2c, Web2c})
@code{TEXPOOL}, @code{TEXMFINI};
suffix @samp{.pool}.

@item tfm
@flindex .tfm
@vindex TFMFONTS
@vindex TEXFONTS
(@TeX{} font metrics, @pxref{Metric files,,, dvips, Dvips})
@code{TFMFONTS}, @code{TEXFONTS};
suffix @samp{.tfm};
dynamic creation program: @code{mktextfm}.

@item Troff fonts
@vindex TRFONTS
(Troff fonts, used by DMP; @pxref{DMP invocation,,, web2c, Web2c})
@code{TRFONTS}.

@item truetype fonts
@flindex .ttf
@flindex .ttc
@vindex TTFONTS
(TrueType outline fonts) @code{TTFONTS}; suffixes @samp{.ttf},
@samp{.ttc}.

@item type1 fonts
@flindex .pfa
@flindex .pfb
@vindex T1FONTS
@vindex T1INPUTS
@vindex TEXPSHEADERS
@vindex DVIPSHEADERS
(Type 1 PostScript outline fonts, @pxref{Glyph files,,, dvips, Dvips})
@code{T1FONTS}, @code{T1INPUTS}, @code{TEXPSHEADERS}, @code{DVIPSHEADERS};
suffixes @samp{.pfa}, @samp{.pfb}.

@item type42 fonts
@vindex T42FONTS
(Type 42 PostScript outline fonts) @code{T42FONTS}.

@item vf
@flindex .vf
@vindex VFFONTS
@vindex TEXFONTS
(virtual fonts, @pxref{Virtual fonts,,, dvips, Dvips})
@code{VFFONTS}, @code{TEXFONTS};
suffix @samp{.vf}.

@item web
@flindex .web
@vindex WEBINPUTS
(WEB input files)
@code{WEBINPUTS};
suffix @samp{.web};
additional suffix @samp{.ch}.

@item web2c files
@vindex WEB2C
(files specific to the web2c implementation)
@code{WEB2C}.
@end table

There are two special cases, because the paths and environment variables
always depend on the name of the program: the variable name is
constructed by converting the program name to upper case, and then
appending @samp{INPUTS}.  Assuming the program is called @samp{foo},
this gives us the following table.

@table @samp
@item other text files
@vindex FOOINPUTS
(text files used by @samp{foo})
@code{FOOINPUTS}.

@item other binary files
@vindex FOOINPUTS
(binary files used by @samp{foo})
@code{FOOINPUTS}.
@end table

If an environment variable by these names are set, the corresponding
@file{texmf.cnf} definition won't be looked at (unless, as usual, the
environment variable value has an extra @samp{:}).  @xref{Default
expansion}.

For the font variables, the intent is that:
@itemize @bullet
@item
@code{TEXFONTS} is the default for everything.

@item
@code{GLYPHFONTS} is the default for bitmap (or, more precisely,
non-metric) files.

@item
Each font format has a variable of its own.

@item
@vindex XDVIFONTS
@vindex DVIPSFONTS
Each program has its own font override path as well; e.g.,
@code{DVIPSFONTS} for Dvipsk.  Again, this is for bitmaps, not metrics.

@end itemize


@node File lookup
@section File lookup

@cindex file lookup
@cindex searching for files
@cindex @TeX{} file lookup

This section describes how Kpathsea searches for most files (bitmap font
searches are the exception, as described in the next section).

Here is the search strategy for a file @var{name}:

@enumerate
@item
If the file format defines default suffixes, and the suffix of
@var{name} name is not already a known suffix for that format, try the
name with each default appended, and use alternative names found in
the fontmaps if necessary.  Example: given @samp{foo.bar}, look for
@samp{foo.bar.tex}.

@item
Search for @var{name}, and if necessary for alternative names found in
the fontmaps.  Example: given @samp{foo.bar}, we also look for
@samp{foo.bar}.

@item
If the file format defines a program to invoke to create missing files,
run it (@pxref{mktex scripts}).
@end enumerate

@cindex extensions, filename
@cindex suffixes, filename
@vindex try_std_extension_first
The order in which we search for ``suffixed'' name (item@tie{}1) or
the ``as-is'' name (item@tie{}2) is controlled by the
@file{try_std_extension_first} configuration value.  The default set
in @file{texmf.cnf} is true, since common suffixes are already
recognized: @samp{babel.sty} will only look for @samp{babel.sty}, not
@samp{babel.sty.tex}, regardless of this setting.

When the suffix is unknown (e.g., @samp{foo.bar}), both names are
always tried; the difference is the order in which they are tried.

@file{try_std_extension_first} only affects names being looked up
which *already* have an extension.  A name without an extension (e.g.,
@samp{tex story}) will always have an extension added first.

@flindex tex-file.c
@findex kpathsea_find_file
This algorithm is implemented in the function
@code{kpathsea_find_file} in the source file
@file{kpathsea/tex-file.c}.  You can watch it in action with the
debugging options (@pxref{Debugging}).


@node Glyph lookup
@section Glyph lookup

@cindex glyph lookup
@cindex searching for glyphs
@cindex @TeX{} glyph lookup

This section describes how Kpathsea searches for a bitmap font in GF or
PK format (or either) given a font name (e.g., @samp{cmr10}) and a
resolution (e.g., 600).

Here is an outline of the search strategy (details in the sections
below) for a file @var{name} at resolution @var{dpi}.  The search stops
at the first successful lookup.

@enumerate
@item
Look for an existing file @var{name}.@var{dpi}@var{format} in the
specified format(s).

@item If @var{name} is an alias for a file @var{f} in the fontmap
file @file{texfonts.map}, look for @var{f}.@var{dpi}.

@item Run an external program (typically named @samp{mktexpk}) to
generate the font (@pxref{mktex scripts})

@item Look for @var{fallback}.@var{dpi}, where @var{fallback} is some
last-resort font (typically @samp{cmr10}).
@end enumerate

@flindex tex-glyph.c
@findex kpathsea_find_glyph
This is implemented in @code{kpathsea_find_glyph} in
@file{kpathsea/tex-glyph.c}.

@menu
* Basic glyph lookup::          Features common to all glyph lookups.
* Fontmap::                     Aliases for fonts.
* Fallback font::               Resolutions and fonts of last resort.
@end menu


@node Basic glyph lookup
@subsection Basic glyph lookup

@cindex basic glyph lookup
@cindex common features in glyph lookup

When Kpathsea looks for a bitmap font @var{name} at resolution @var{dpi}
in a format @var{format}, it first checks each directory in the search
path for a file @samp{@var{name}.@var{dpi}@var{format}}; for example,
@samp{cmr10.600pk}.  Kpathsea looks for a PK file first, then a GF file.

If that fails, Kpathsea looks for
@samp{dpi@var{dpi}/@var{name}.@var{format}}; for example,
@samp{dpi600/cmr10.pk}. This is how fonts are typically stored on
filesystems (such as DOS) that permit only three-character extensions.

@cindex tolerance for glyph lookup
@cindex glyph lookup bitmap tolerance
@findex KPSE_BITMAP_TOLERANCE
If that fails, Kpathsea looks for a font with a close-enough @var{dpi}.
``Close enough'' is defined by the macro @code{KPSE_BITMAP_TOLERANCE} in
@file{kpathsea/tex-glyph.h} to be @code{@var{dpi} / 500 + 1}.  This is
slightly more than the 0.2% minimum allowed by the DVI standard
(@url{@var{CTAN:}/dviware/driv-standard/level-0}).


@node Fontmap
@subsection Fontmap

@cindex fontmap files
@cindex font alias files
@cindex aliases for fonts

@flindex texfonts.map
If a bitmap font or metric file is not found with the original name (see
the previous section), Kpathsea looks through any @dfn{fontmap} files
for an @dfn{alias} for the original font name.  These files are named
@file{texfonts.map} and searched for along the @code{TEXFONTMAPS}
environment/config file variable.  All @file{texfonts.map} files that
are found are read; earlier definitions override later ones.

This feature is intended to help in two respects:

@enumerate

@item
@cindex fontnames, arbitrary length
An alias name is limited in length only by available memory, not by your
filesystem.  Therefore, if you want to ask for @samp{Times-Roman}
instead of @file{ptmr}, you can (you get @samp{ptmr8r}).

@item
@cindex circle fonts
@flindex lcircle10
A few fonts have historically had multiple names: specifically,
La@TeX{}'s ``circle font'' has variously been known as @file{circle10},
@file{lcircle10}, and @file{lcirc10}.  Aliases can make all the names
equivalent, so that it no longer matters what the name of the installed
file is; @TeX{} documents will find their favorite name.

@end enumerate

The format of fontmap files is straightforward:

@itemize @bullet
@cindex comments, in fontmap files
@item Comments start with @samp{%} and continue to the end of the line.
@cindex whitespace, in fontmap files
@item Blank lines are ignored.
@item Each nonblank line is broken up into a series of @dfn{words}:
  a sequence of non-whitespace characters.
@findex include @r{fontmap directive}
@item If the first word is @samp{include}, the second word is used as
  a filename, and it is searched for and read.
@item Otherwise, the first word on each line is the true filename;
@item the second word is the alias;
@item subsequent words are ignored.
@end itemize

If an alias has an extension, it matches only those files with that
extension; otherwise, it matches anything with the same root, regardless
of extension.  For example, an alias @samp{foo.tfm} matches only when
@file{foo.tfm} is being searched for; but an alias @samp{foo} matches
@file{foo.vf}, @file{foo.600pk}, etc.

As an example, here is an excerpt from the @file{texfonts.map} in the
Web2c distribution.  It makes the circle fonts equivalent and includes
automatically generated maps for most PostScript fonts available from
various font suppliers.

@example
circle10        lcircle10
circle10        lcirc10
lcircle10       circle10
lcircle10       lcirc10
lcirc10         circle10
lcirc10         lcircle10
@dots{}
include adobe.map
include apple.map
include bitstrea.map
@dots{}
@end example

Fontmaps are implemented in the file @file{kpathsea/fontmap.c}.
The Fontname distribution has much more information on font naming
(@pxref{Introduction,,, fontname, Filenames for @TeX{} fonts}).


@node Fallback font
@subsection Fallback font

@cindex fallback font
@cindex fallback resolutions
@cindex font of last resort
@cindex resolutions, last-resort
@cindex last-resort font

@vindex DVIPSSIZES
@vindex XDVISIZES
@vindex DVILJSIZES
@vindex TEXSIZES
@vindex default_texsizes
If a bitmap font cannot be found or created at the requested size,
Kpathsea looks for the font at a set of @dfn{fallback resolutions}.  You
specify these resolutions as a colon-separated list (like search paths).
Kpathsea looks first for a program-specific environment variable (e.g.,
@code{DVIPSSIZES} for Dvipsk), then the environment variable
@code{TEXSIZES}, then a default specified at compilation time (the Make
variable @code{default_texsizes}).  You can set this list to be empty if
you prefer to find fonts at their stated size or not at all.

@flindex cmr10@r{, as fallback font}
@findex kpathsea_init_prog
Finally, if the font cannot be found even at the fallback resolutions,
Kpathsea looks for a fallback font, typically @file{cmr10}.  Programs
must enable this feature by  calling @code{kpathsea_init_prog}
(@pxref{Calling sequence}); the default is no fallback font.


@node Suppressing warnings
@section Suppressing warnings

@cindex warnings, suppressing
@cindex suppressing warnings

@vindex TEX_HUSH
Kpathsea provides a way to suppress selected usually-harmless warnings;
this is useful at large sites where most users are not administrators,
and thus the warnings are merely a source of confusion, not a help.  To
do this, you set the environment variable or configuration file value
@code{TEX_HUSH} to a colon-separated list of values.  Here are the
possibilities:

@vtable @samp
@item all
Suppress everything possible.

@item checksum
@cindex mismatched checksum warnings
Suppress mismatched font checksum warnings.

@item lostchar
@cindex missing character warnings
Suppress warnings when a character is missing from a font that a DVI or
VF file tries to typeset.

@item none
Don't suppress any warnings.

@item readable
@cindex unreadable file warnings
Suppress warnings about attempts to access a file whose permissions
render it unreadable.

@item special
@cindex unknown special warnings
@findex \special@r{, suppressing warnings about}
Suppresses warnings about an unimplemented or unparsable
@samp{\special} command.
@end vtable

@noindent @file{tex-hush.c} defines the function that checks the
variable value.  Each driver implements its own checks where
appropriate.


@node Programming
@chapter Programming

This chapter is for programmers who wish to use Kpathsea.
@xref{Introduction}, for the conditions under which you may do so.

@menu
* Overview: Programming overview.         Introduction.
* Calling sequence::                      Specifics of what to call.
* Program-specific files::                How to handle these.
* Config: Programming with config files.  Getting info from texmf.cnf.
@end menu


@node Programming overview
@section Programming overview

@cindex programming overview
@cindex overview of programming with Kpathsea

Aside from this manual, your best source of information is the source
to the programs that use Kpathsea (@pxref{Introduction}).  Of those,
Dviljk is probably the simplest, and hence a good place to start.
Xdvik adds VF support and the complication of X resources.  Dvipsk
adds the complication of its own config files.  Web2c is source code I
also maintain, so it uses Kpathsea rather straightforwardly, but is of
course complicated by the Web to C translation.  Finally, Kpsewhich is
a small utility program whose sole purpose is to exercise the main
path-searching functionality.

@cindex re-entrant API
@cindex API, re-entrant
When looking at these program sources, you should know that previous
versions of the library had a different programming interface, to
support re-entrancy.  In that interface the library function names
were prefixed with @code{kpse_} instead of @code{kpathsea_}, and they
did not need an instance variable as first argument.  This change was
made in 2009.  Some of the programs mentioned above may still be using
the previous interface.

@flindex pathsearch.h
@flindex tex-file.h
@flindex tex-glyph.h
@flindex kpathsea.h
Beyond these examples, the @file{.h} files in the Kpathsea source
describe the interfaces and functionality (and of course the @file{.c}
files define the actual routines, which are the ultimate documentation).
@file{pathsearch.h} declares the basic searching routine.
@file{tex-file.h} and @file{tex-glyph.h} define the interfaces for
looking up particular kinds of files.  In view of the way the headers
depend on each other, it is recommended to use @code{#include
<kpathsea/kpathsea.h>}, which includes every Kpathsea header.

@flindex config.h
@flindex c-auto.h
If you want to include only specific headers, you should still consider
including @file{kpathsea/config.h} before including any other Kpathsea
header, as it provides symbols used in the other headers.  Note that
@file{kpathsea/config.h} includes @file{kpathsea/c-auto.h}, which is
generated by Autoconf.

@cindex file types, registering new
The library provides no way for an external program to register new file
types: @file{tex-file.[ch]} must be modified to do this. For example,
Kpathsea has support for looking up Dvips config files, even though no
program other than Dvips will likely ever want to do so.  I felt this
was acceptable, since along with new file types should also come new
defaults in @file{texmf.cnf} (and its descendant @file{paths.h}), since
it's simplest for users if they can modify one configuration file for
all kinds of paths.

Kpathsea does not parse any formats itself; it barely opens any files.
Its primary purpose is to return filenames.  The GNU font utilities does
contain libraries to read TFM, GF, and PK files, as do the programs
above, of course.


@node Calling sequence
@section Calling sequence

@cindex programming with Kpathsea
@cindex calling sequence

The typical way to use Kpathsea in your program goes something like this:

@enumerate

@item
@findex kpathsea_new
Call @code{kpathsea_new} to create a new library instance. This variable
must be passed as the first argument to all the following library functions.
The rest of this manual will be using @code{kpse} as a placeholder for
the name of this variable.

@item
@findex kpathsea_set_program_name
@vindex argv[0]
Call @code{kpathsea_set_program_name} with @code{argv[0]} as the second
argument; the third argument is a string or @code{NULL}.  The third
argument is used by Kpathsea as the program name for the
@code{.@var{program}} feature of config files (@pxref{Config files}).
If the third argument is @code{NULL}, the value of the second argument
is used.  This function must be called before any other use of the
Kpathsea library.

@vindex kpse->invocation_name
@vindex kpse->invocation_short_name
@vindex kpse->program_name
@cindex error message macros
@code{kpathsea_set_program_name} always sets the variables
@code{kpse->invocation_name} and @code{kpse->invocation_short_name}.
These variables are used in the error message macros defined in
@file{kpathsea/lib.h}.  It sets the variable
@code{kpse->program_name} to the program name it uses.

@vindex KPATHSEA_DEBUG
It also initializes debugging options based on the environment
variable @code{KPATHSEA_DEBUG} (if that is set).

@cindex SELFAUTOLOC
@cindex SELFAUTODIR
@cindex SELFAUTOPARENT
@cindex symlinks, resolving
@cindex expanding symlinks
Finally, it sets the environment variables @code{SELFAUTOLOC}, @code{SELFAUTODIR}
and @code{SELFAUTOPARENT} to the location, parent and grandparent
directory of the executable, removing @file{.} and @file{..} path
elements and resolving symbolic links.  These are used in the default
configuration file to allow people to invoke TeX from anywhere.  You
can use @samp{kpsewhich --expand-var=\$SELFAUTOLOC}, etc., to see the
values.

@item
@vindex kpse->debug @r{variable}
@cindex debugging options, in Kpathsea-using program
Set debugging options. @xref{Debugging}.  If your program doesn't have a
debugging option already, you can define one and set
@code{kpse->debug} to the number that the user supplies (as in Dviljk
and Web2c), or you can just omit this altogether (people can always set
@code{KPATHSEA_DEBUG}).  If you do have runtime debugging already, you
need to merge Kpathsea's options with yours (as in Dvipsk and Xdvik).

@item
@vindex client_path @r{in @code{kpse->format_info}}
@vindex kpse->format_info
@flindex resident.c
@cindex config files, for Kpathsea-using programs
If your program has its own configuration files that can define search
paths, you should assign those paths to the @code{client_path} member in
the appropriate element of the @code{kpse->format_info} array.  (This
array is indexed by file type; see @file{tex-file.h}.)  See
@file{resident.c} in Dvipsk for an example.

@item
@findex kpathsea_init_prog
@flindex proginit.h
Call @code{kpathsea_init_prog} (see @file{proginit.c}). It's useful for the
DVI drivers, at least, but for other programs it may be simpler to
extract the parts of it that actually apply.  This does not initialize
any paths, it just looks for (and sets) certain environment variables
and other random information.  (A search path is always initialized at
the first call to find a file of that type; this eliminates much useless
work, e.g., initializing the Bib@TeX{} search paths in a DVI driver.)

@item
@findex kpathsea_find_file
The routine to actually find a file of type @var{format} is
@file{kpathsea_find_file}.  You can call
@code{kpathsea_find_file} after doing only the first and second of the
initialization steps above---Kpathsea automatically reads the
@file{texmf.cnf} generic config files, looks for environment variables,
and does expansions at the first lookup.

@item
To find PK and/or GF bitmap fonts, the routine
is @code{kpathsea_find_glyph}, defined in
@file{tex-glyph.h}. This returns a structure in addition to the
resultant filename, because fonts can be found in so many ways. See the
documentation in the source.

@item
@findex kpathsea_open_file
To actually open a file, not just return a filename, call
@code{kpathsea_open_file}.  This function takes the name to look up and a
Kpathsea file format as arguments, and returns the usual @code{FILE *}.
It always assumes the file must exist, and thus will search the disk if
necessary (unless the search path specified @samp{!!}, etc.).  In other
words, if you are looking up a VF or some other file that need not
exist, don't use this.

@item
@findex kpathsea_out_name_ok
@TeX{} can write output files, via the @code{\openout} primitive; this opens
a security hole vulnerable to Trojan horse attack: an unwitting user could
run a @TeX{} program that overwrites, say, @file{~/.rhosts}.  Analogous
security holes exist for many other programs.  To alleviate this, there is a
configuration variable @code{openout_any}, which selects one of three levels
of security.  When it is set to @samp{a} (for ``any''), no restrictions are
imposed.  When it is set to @samp{r} (for ``restricted''), filenames
beginning with @samp{.} are disallowed (except @file{.tex} because @LaTeX{}
needs it).  When it is set to @samp{p} (for ``paranoid'') additional
restrictions are imposed: an absolute filename must refer to a file in (a
subdirectory) of @code{TEXMFOUTPUT}, and any attempt to go up a directory
level is forbidden (that is, paths may not contain a @samp{..} component). 
The paranoid setting is the default.  (For backwards compatibility, @samp{y}
and @samp{1} are synonyms of @samp{a}, while @samp{n} and @samp{0} are
synonyms for @samp{r}.) The function @code{kpathsea_out_name_ok}, with a
filename as second argument, returns @code{true} if that filename is
acceptable to be opend for output or @code{false} otherwise.

@item
@findex kpathsea_in_name_ok
Similarly, the function @code{kpathsea_in_name_ok}, with a filename as
second argument, returns @code{true} if that filename is acceptable to be
opend for input or @code{false} otherwise, depending on the value of the
configuration variable @code{openin_any} (with @samp{a} as default).

@item
@findex kpathsea_finish
To close the kpathsea library instance you are using, call
@code{kpathsea_finish}.  This function closes any open log files and
frees the memory used by the instance.

@end enumerate

@cindex hash table routines
@cindex memory allocation routines
@cindex string routines
@cindex reading arbitrary-length lines
@cindex input lines, reading
@cindex lines, reading arbitrary-length
Kpathsea also provides many utility routines. Some are generic: hash
tables, memory allocation, string concatenation and copying, string
lists, reading input lines of arbitrary length, etc. Others are
filename-related: default path, tilde, and variable expansion,
@code{stat} calls, etc. (Perhaps someday I'll move the former to a
separate library.)

@flindex c-*.h
@pindex autoconf@r{, recommended}
The @file{c-*.h} header files can also help your program adapt to many
different systems.  You will almost certainly want to use Autoconf and
probably Automake for configuring and building your software if you use
Kpathsea; I strongly recommend using Autoconf and Automake regardless.
They are available from @url{ftp://ftp.gnu.og/pub/gnu/}.


@node Program-specific files
@section Program-specific files

Many programs will need to find some configuration files.  Kpathsea
contains some support to make it easy to place them in their own
directories.  The Standard @TeX{} directory structure (@pxref{Top,,
Introduction, tds, A Directory Structure for @TeX{} files}), specifies
that such files should go into a subdirectory named after the program,
like @samp{texmf/ttf2pk}.

Two formats, @samp{kpse_program_text_format} and
@samp{kpse_program_binary_format}, use @code{.:$TEXMF/@var{program}//}
as their compiled-in search path.  To override this default, you can
use the variable @code{@var{PROGRAM}INPUTS} in the environment and/or
@samp{texmf.cnf}.  That is to say, the name of the variable is
constructed by converting the name of the program to upper case, and
appending @code{INPUTS}.

The only difference between these two formats is whether
@code{kpathsea_open_file} will open the files it finds in text or binary
mode.


@node Programming with config files
@section Programming with config files

@cindex programming with config files
@cindex config files, programming with

You can (and probably should) use the same @code{texmf.cnf}
configuration file that Kpathsea uses for your program.  This helps
installers by keeping all configuration in one place.

@findex kpathsae_var_value
@flindex variable.h
@vindex shell_escape@r{, example for code}
To retrieve a value @var{var} from config files, the best way is to call
@code{kpathsea_var_value} on the string @code{@var{var}}.  This will look
first for an environment variable @var{var}, then a config file value.
The result will be the value found or @samp{NULL}.  This function is
declared in @file{kpathsea/variable.h}.  For an example, see the
@code{shell_escape} code in @file{web2c/lib/texmfmp.c}.

The routine to do variable expansion in the context of a search path (as
opposed to simply retrieving a value) is @code{kpathsea_var_expand}, also
declared in @file{kpathsea/variable.h}.  It's generally only necessary
to set the search path structure components as explained in the previous
section, rather than using this yourself.

@findex kpathsea_cnf_get
@flindex cnf.h
If for some reason you want to retrieve a value @emph{only} from a
config file, not automatically looking for a corresponding environment
variable, call @code{kpathsea_cnf_get} (declared in @file{kpathsea/cnf.h})
with the string @var{var}.

No initialization calls are needed.


@node Index
@unnumbered Index

@printindex cp

@bye
