autoconf: Makefile Substitutions

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1 4.8 Substitutions in Makefiles
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1 Each subdirectory in a distribution that contains something to be
1 compiled or installed should come with a file `Makefile.in', from which
1 `configure' creates a file `Makefile' in that directory.  To create
1 `Makefile', `configure' performs a simple variable substitution,
1 replacing occurrences of `@VARIABLE@' in `Makefile.in' with the value
1 that `configure' has determined for that variable.  Variables that are
1 substituted into output files in this way are called "output
1 variables".  They are ordinary shell variables that are set in
1 `configure'.  To make `configure' substitute a particular variable into
1 the output files, the macro `AC_SUBST' must be called with that
1 variable name as an argument.  Any occurrences of `@VARIABLE@' for
1 other variables are left unchanged.  ⇒Setting Output Variables,
1 for more information on creating output variables with `AC_SUBST'.
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1    A software package that uses a `configure' script should be
1 distributed with a file `Makefile.in', but no makefile; that way, the
1 user has to properly configure the package for the local system before
1 compiling it.
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1    ⇒Makefile Conventions (standards)Makefile Conventions, for
1 more information on what to put in makefiles.
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Menu

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· Preset Output Variables     Output variables that are always set
· Installation Directory Variables  Other preset output variables
· Changed Directory Variables  Warnings about `datarootdir'
· Build Directories           Supporting multiple concurrent compiles
· Automatic Remaking          Makefile rules for configuring
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