diff --git a/doc/manual/expressions/builder-syntax.xml b/doc/manual/expressions/builder-syntax.xml deleted file mode 100644 index e51bade44..000000000 --- a/doc/manual/expressions/builder-syntax.xml +++ /dev/null @@ -1,119 +0,0 @@ -
- -Builder Syntax - -Build script for GNU Hello -(<filename>builder.sh</filename>) - -source $stdenv/setup - -PATH=$perl/bin:$PATH - -tar xvfz $src -cd hello-* -./configure --prefix=$out -make -make install - - - shows the builder referenced -from Hello's Nix expression (stored in -pkgs/applications/misc/hello/ex-1/builder.sh). -The builder can actually be made a lot shorter by using the -generic builder functions provided by -stdenv, but here we write out the build steps to -elucidate what a builder does. It performs the following -steps: - - - - - - When Nix runs a builder, it initially completely clears the - environment (except for the attributes declared in the - derivation). For instance, the PATH variable is - emptyActually, it's initialised to - /path-not-set to prevent Bash from setting it - to a default value.. This is done to prevent - undeclared inputs from being used in the build process. If for - example the PATH contained - /usr/bin, then you might accidentally use - /usr/bin/gcc. - - So the first step is to set up the environment. This is - done by calling the setup script of the - standard environment. The environment variable - stdenv points to the location of the standard - environment being used. (It wasn't specified explicitly as an - attribute in , but - mkDerivation adds it automatically.) - - - - - - Since Hello needs Perl, we have to make sure that Perl is in - the PATH. The perl environment - variable points to the location of the Perl package (since it - was passed in as an attribute to the derivation), so - $perl/bin is the - directory containing the Perl interpreter. - - - - - - Now we have to unpack the sources. The - src attribute was bound to the result of - fetching the Hello source tarball from the network, so the - src environment variable points to the location in - the Nix store to which the tarball was downloaded. After - unpacking, we cd to the resulting source - directory. - - The whole build is performed in a temporary directory - created in /tmp, by the way. This directory is - removed after the builder finishes, so there is no need to clean - up the sources afterwards. Also, the temporary directory is - always newly created, so you don't have to worry about files from - previous builds interfering with the current build. - - - - - - GNU Hello is a typical Autoconf-based package, so we first - have to run its configure script. In Nix - every package is stored in a separate location in the Nix store, - for instance - /nix/store/9a54ba97fb71b65fda531012d0443ce2-hello-2.1.1. - Nix computes this path by cryptographically hashing all attributes - of the derivation. The path is passed to the builder through the - out environment variable. So here we give - configure the parameter - --prefix=$out to cause Hello to be installed in - the expected location. - - - - - - Finally we build Hello (make) and install - it into the location specified by out - (make install). - - - - - -If you are wondering about the absence of error checking on the -result of various commands called in the builder: this is because the -shell script is evaluated with Bash's option, -which causes the script to be aborted if any command fails without an -error check. - -
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