lix/doc/manual/expressions/debug-build.xml

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2014-08-27 16:41:09 +00:00
<section xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
version="5.0"
xml:id="sec-debug-build">
<title>Debugging Build Failures</title>
<para>At the beginning of each phase, the set of all shell variables
is written to the file <filename>env-vars</filename> at the top-level
build directory. This is useful for debugging: it allows you to
recreate the environment in which a build was performed. For
instance, if a build fails, then assuming you used the
<option>-K</option> flag, you can go to the output directory and
<quote>switch</quote> to the environment of the builder:
<screen>
$ nix-build -K ./foo.nix
... fails, keeping build directory `/tmp/nix-1234-0'
$ cd /tmp/nix-1234-0
$ source env-vars
<lineannotation>(edit some files...)</lineannotation>
$ make
<lineannotation>(execution continues with the same GCC, make, etc.)</lineannotation></screen>
</para>
</section>