diff options
Diffstat (limited to 'third_party/nix/doc/manual/expressions/simple-building-testing.xml')
| -rw-r--r-- | third_party/nix/doc/manual/expressions/simple-building-testing.xml | 84 |
1 files changed, 0 insertions, 84 deletions
diff --git a/third_party/nix/doc/manual/expressions/simple-building-testing.xml b/third_party/nix/doc/manual/expressions/simple-building-testing.xml deleted file mode 100644 index 7326a3e76a..0000000000 --- a/third_party/nix/doc/manual/expressions/simple-building-testing.xml +++ /dev/null @@ -1,84 +0,0 @@ -<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-building-simple'> - -<title>Building and Testing</title> - -<para>You can now try to build Hello. Of course, you could do -<literal>nix-env -i hello</literal>, but you may not want to install a -possibly broken package just yet. The best way to test the package is by -using the command <command linkend="sec-nix-build">nix-build</command>, -which builds a Nix expression and creates a symlink named -<filename>result</filename> in the current directory: - -<screen> -$ nix-build -A hello -building path `/nix/store/632d2b22514d...-hello-2.1.1' -hello-2.1.1/ -hello-2.1.1/intl/ -hello-2.1.1/intl/ChangeLog -<replaceable>...</replaceable> - -$ ls -l result -lrwxrwxrwx ... 2006-09-29 10:43 result -> /nix/store/632d2b22514d...-hello-2.1.1 - -$ ./result/bin/hello -Hello, world!</screen> - -The <link linkend='opt-attr'><option>-A</option></link> option selects -the <literal>hello</literal> attribute. This is faster than using the -symbolic package name specified by the <literal>name</literal> -attribute (which also happens to be <literal>hello</literal>) and is -unambiguous (there can be multiple packages with the symbolic name -<literal>hello</literal>, but there can be only one attribute in a set -named <literal>hello</literal>).</para> - -<para><command>nix-build</command> registers the -<filename>./result</filename> symlink as a garbage collection root, so -unless and until you delete the <filename>./result</filename> symlink, -the output of the build will be safely kept on your system. You can -use <command>nix-build</command>’s <option -linkend='opt-out-link'>-o</option> switch to give the symlink another -name.</para> - -<para>Nix has transactional semantics. Once a build finishes -successfully, Nix makes a note of this in its database: it registers -that the path denoted by <envar>out</envar> is now -<quote>valid</quote>. If you try to build the derivation again, Nix -will see that the path is already valid and finish immediately. If a -build fails, either because it returns a non-zero exit code, because -Nix or the builder are killed, or because the machine crashes, then -the output paths will not be registered as valid. If you try to build -the derivation again, Nix will remove the output paths if they exist -(e.g., because the builder died half-way through <literal>make -install</literal>) and try again. Note that there is no -<quote>negative caching</quote>: Nix doesn't remember that a build -failed, and so a failed build can always be repeated. This is because -Nix cannot distinguish between permanent failures (e.g., a compiler -error due to a syntax error in the source) and transient failures -(e.g., a disk full condition).</para> - -<para>Nix also performs locking. If you run multiple Nix builds -simultaneously, and they try to build the same derivation, the first -Nix instance that gets there will perform the build, while the others -block (or perform other derivations if available) until the build -finishes: - -<screen> -$ nix-build -A hello -waiting for lock on `/nix/store/0h5b7hp8d4hqfrw8igvx97x1xawrjnac-hello-2.1.1x'</screen> - -So it is always safe to run multiple instances of Nix in parallel -(which isn’t the case with, say, <command>make</command>).</para> - -<para>If you have a system with multiple CPUs, you may want to have -Nix build different derivations in parallel (insofar as possible). -Just pass the option <link linkend='opt-max-jobs'><option>-j -<replaceable>N</replaceable></option></link>, where -<replaceable>N</replaceable> is the maximum number of jobs to be run -in parallel, or set. Typically this should be the number of -CPUs.</para> - -</section> |