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(Released under the old-style GNU documentation license;
 see sources or other output files for full text.)

3 Prerequisites
***************

Overall, building the TeX Live programs, when using all libraries from
the TL source tree, requires C and C++11 compilers, GNU 'make', and
Python.

   * If 'make' from your 'PATH' is not GNU 'make', you can set the
     'MAKE' environment variable to whatever is necessary.

     GNU 'make' is required only because of third-party libraries,
     notably FreeType.  Automake/Autoconf output in general, and the
     TL-maintained directories, work with any reasonable 'make'.(1)

   * A C++11 compiler is similarly required because of the third-party
     libraries ICU and HarfBuzz (at least); the program 'dvisvgm' also
     requires C++11.  It is possible to build what remains with older
     compilers, but you have to remove the C++11-dependent sources.  See
     Build one package.

   * Python is required by ICU tests.  (If you know how to disable these
     tests and thus eliminate the requirement, please write.)

   A few programs in the tree have additional requirements:

'web2c'
     requires 'perl' for some tests run by 'make check'.  Incidentally,
     the TeX Live installer ('install-tl') and manager ('tlmgr') are
     also written in Perl, but this does not matter for compiling the
     sources.

'xdvik'
'xpdfopen'
     require X11 headers and libraries, typically in devel(opment)
     packages that are not installed by default.

'xetex'
     requires 'fontconfig' (again both headers and library), or, for
     MacOS only, the 'ApplicationServices' and 'Cocoa' frameworks.

'xindy'
     requires GNU 'clisp', 'libsigsegv', and 'libiconv'; additionally,
     to build the rules and/or documentation: 'perl', 'latex',
     'pdflatex'.

Lacking the required tools, building these programs must avoided, e.g.,
'configure --without-x --disable-xetex --disable-xindy'

   Modifying source files induces more requirements, as one might
expect:

   * Modification of any '.y' or '.l' source files requires 'bison' or
     'flex' to update the corresponding C sources.

   * Modification of the sources for '.info' files requires 'makeinfo'.

   * Modification of any part of the build system (M4 macros,
     'configure.ac', 'Makefile.am', or their fragments) requires GNU M4,
     GNU Autoconf, GNU Automake, and GNU Libtool to update the generated
     files.  Furthermore, to reliably reproduce the build files, the
     latest original GNU releases of these tools must be used, not any
     distro packaging of them.  See Build system tools, for more
     discussion.

   If you haven't modified any source files, and infrastructure tools
such as 'autoconf' or 'makeinfo' are still being run, check your
timestamps--notably, 'use-commit-times' must be set to 'yes' in your
Subversion configuration (see Build system tools).  No infrastructure
tools are needed to do a normal build (barring bugs).

   ---------- Footnotes ----------

   (1) There is one exception in TL: the 'tangle-sh' and related rules
use '$@' to mean the target name, a feature not present in all 'make's.
This could be alleviated by laborious editing, but since there's no way
to avoid GNU 'make' for builds of the entire tree, it does not seem
worth the trouble.

