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diff --git a/doc/manual/command-ref/nix-shell.xml b/doc/manual/command-ref/nix-shell.xml new file mode 100644 index 000000000000..c64c93ec3ac2 --- /dev/null +++ b/doc/manual/command-ref/nix-shell.xml @@ -0,0 +1,374 @@ +<refentry 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-nix-shell"> + +<refmeta> + <refentrytitle>nix-shell</refentrytitle> + <manvolnum>1</manvolnum> + <refmiscinfo class="source">Nix</refmiscinfo> + <refmiscinfo class="version"><xi:include href="../version.txt" parse="text"/></refmiscinfo> +</refmeta> + +<refnamediv> + <refname>nix-shell</refname> + <refpurpose>start an interactive shell based on a Nix expression</refpurpose> +</refnamediv> + +<refsynopsisdiv> + <cmdsynopsis> + <command>nix-shell</command> + <arg><option>--arg</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg> + <arg><option>--argstr</option> <replaceable>name</replaceable> <replaceable>value</replaceable></arg> + <arg> + <group choice='req'> + <arg choice='plain'><option>--attr</option></arg> + <arg choice='plain'><option>-A</option></arg> + </group> + <replaceable>attrPath</replaceable> + </arg> + <arg><option>--command</option> <replaceable>cmd</replaceable></arg> + <arg><option>--run</option> <replaceable>cmd</replaceable></arg> + <arg><option>--exclude</option> <replaceable>regexp</replaceable></arg> + <arg><option>--pure</option></arg> + <group choice='req'> + <group choice='plain'> + <group> + <arg choice='plain'><option>--packages</option></arg> + <arg choice='plain'><option>-p</option></arg> + </group> + <replaceable>packages</replaceable> + </group> + <arg><replaceable>path</replaceable></arg> + </group> + </cmdsynopsis> +</refsynopsisdiv> + +<refsection><title>Description</title> + +<para>The command <command>nix-shell</command> will build the +dependencies of the specified derivation, but not the derivation +itself. It will then start an interactive shell in which all +environment variables defined by the derivation +<replaceable>path</replaceable> have been set to their corresponding +values, and the script <literal>$stdenv/setup</literal> has been +sourced. This is useful for reproducing the environment of a +derivation for development.</para> + +<para>If <replaceable>path</replaceable> is not given, +<command>nix-shell</command> defaults to +<filename>shell.nix</filename> if it exists, and +<filename>default.nix</filename> otherwise.</para> + +<para>If <replaceable>path</replaceable> starts with +<literal>http://</literal> or <literal>https://</literal>, it is +interpreted as the URL of a tarball that will be downloaded and +unpacked to a temporary location. The tarball must include a single +top-level directory containing at least a file named +<filename>default.nix</filename>.</para> + +<para>If the derivation defines the variable +<varname>shellHook</varname>, it will be evaluated after +<literal>$stdenv/setup</literal> has been sourced. Since this hook is +not executed by regular Nix builds, it allows you to perform +initialisation specific to <command>nix-shell</command>. For example, +the derivation attribute + +<programlisting> +shellHook = + '' + echo "Hello shell" + ''; +</programlisting> + +will cause <command>nix-shell</command> to print <literal>Hello shell</literal>.</para> + +</refsection> + + +<refsection><title>Options</title> + +<para>All options not listed here are passed to <command>nix-store +--realise</command>, except for <option>--arg</option> and +<option>--attr</option> / <option>-A</option> which are passed to +<command>nix-instantiate</command>. <phrase condition="manual">See +also <xref linkend="sec-common-options" />.</phrase></para> + +<variablelist> + + <varlistentry><term><option>--command</option> <replaceable>cmd</replaceable></term> + + <listitem><para>In the environment of the derivation, run the + shell command <replaceable>cmd</replaceable>. This command is + executed in an interactive shell. (Use <option>--run</option> to + use a non-interactive shell instead.) However, a call to + <literal>exit</literal> is implicitly added to the command, so the + shell will exit after running the command. To prevent this, add + <literal>return</literal> at the end; e.g. <literal>--command + "echo Hello; return"</literal> will print <literal>Hello</literal> + and then drop you into the interactive shell. This can be useful + for doing any additional initialisation.</para></listitem> + + </varlistentry> + + <varlistentry><term><option>--run</option> <replaceable>cmd</replaceable></term> + + <listitem><para>Like <option>--command</option>, but executes the + command in a non-interactive shell. This means (among other + things) that if you hit Ctrl-C while the command is running, the + shell exits.</para></listitem> + + </varlistentry> + + <varlistentry><term><option>--exclude</option> <replaceable>regexp</replaceable></term> + + <listitem><para>Do not build any dependencies whose store path + matches the regular expression <replaceable>regexp</replaceable>. + This option may be specified multiple times.</para></listitem> + + </varlistentry> + + <varlistentry><term><option>--pure</option></term> + + <listitem><para>If this flag is specified, the environment is + almost entirely cleared before the interactive shell is started, + so you get an environment that more closely corresponds to the + “real” Nix build. A few variables, in particular + <envar>HOME</envar>, <envar>USER</envar> and + <envar>DISPLAY</envar>, are retained. Note that + <filename>~/.bashrc</filename> and (depending on your Bash + installation) <filename>/etc/bashrc</filename> are still sourced, + so any variables set there will affect the interactive + shell.</para></listitem> + + </varlistentry> + + <varlistentry><term><option>--packages</option> / <option>-p</option></term> + + <listitem><para>Set up an environment in which the specified + packages are present. The command line arguments are interpreted + as attribute names inside the Nix Packages collection. Thus, + <literal>nix-shell -p libjpeg openjdk</literal> will start a shell + in which the packages denoted by the attribute names + <varname>libjpeg</varname> and <varname>openjdk</varname> are + present.</para></listitem> + + </varlistentry> + + <varlistentry><term><option>-i</option> <replaceable>interpreter</replaceable></term> + + <listitem><para>The chained script interpreter to be invoked by + <command>nix-shell</command>. Only applicable in + <literal>#!</literal>-scripts (described <link + linkend="ssec-nix-shell-shebang">below</link>).</para> + + </listitem></varlistentry> + +</variablelist> + +<para>The following common options are supported:</para> + +<variablelist condition="manpage"> + <xi:include href="opt-common.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(//db:variablelist[@xml:id='opt-common']/*)" /> +</variablelist> + +</refsection> + + +<refsection><title>Environment variables</title> + +<variablelist> + + <varlistentry><term><envar>NIX_BUILD_SHELL</envar></term> + + <listitem><para>Shell used to start the interactive environment. + Defaults to the <command>bash</command> found in <envar>PATH</envar>.</para></listitem> + + </varlistentry> + +</variablelist> + +</refsection> + + +<refsection><title>Examples</title> + +<para>To build the dependencies of the package Pan, and start an +interactive shell in which to build it: + +<screen> +$ nix-shell '<nixpkgs>' -A pan +[nix-shell]$ unpackPhase +[nix-shell]$ cd pan-* +[nix-shell]$ configurePhase +[nix-shell]$ buildPhase +[nix-shell]$ ./pan/gui/pan +</screen> + +To clear the environment first, and do some additional automatic +initialisation of the interactive shell: + +<screen> +$ nix-shell '<nixpkgs>' -A pan --pure \ + --command 'export NIX_DEBUG=1; export NIX_CORES=8; return' +</screen> + +Nix expressions can also be given on the command line. For instance, +the following starts a shell containing the packages +<literal>sqlite</literal> and <literal>libX11</literal>: + +<screen> +$ nix-shell -E 'with import <nixpkgs> { }; runCommand "dummy" { buildInputs = [ sqlite xorg.libX11 ]; } ""' +</screen> + +A shorter way to do the same is: + +<screen> +$ nix-shell -p sqlite xorg.libX11 +[nix-shell]$ echo $NIX_LDFLAGS +… -L/nix/store/j1zg5v…-sqlite-3.8.0.2/lib -L/nix/store/0gmcz9…-libX11-1.6.1/lib … +</screen> + +The <command>-p</command> flag looks up Nixpkgs in the Nix search +path. You can override it by passing <option>-I</option> or setting +<envar>NIX_PATH</envar>. For example, the following gives you a shell +containing the Pan package from a specific revision of Nixpkgs: + +<screen> +$ nix-shell -p pan -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/8a3eea054838b55aca962c3fbde9c83c102b8bf2.tar.gz + +[nix-shell:~]$ pan --version +Pan 0.139 +</screen> + +</para> + +</refsection> + + +<refsection xml:id="ssec-nix-shell-shebang"><title>Use as a <literal>#!</literal>-interpreter</title> + +<para>You can use <command>nix-shell</command> as a script interpreter +to allow scripts written in arbitrary languages to obtain their own +dependencies via Nix. This is done by starting the script with the +following lines: + +<programlisting> +#! /usr/bin/env nix-shell +#! nix-shell -i <replaceable>real-interpreter</replaceable> -p <replaceable>packages</replaceable> +</programlisting> + +where <replaceable>real-interpreter</replaceable> is the “real” script +interpreter that will be invoked by <command>nix-shell</command> after +it has obtained the dependencies and initialised the environment, and +<replaceable>packages</replaceable> are the attribute names of the +dependencies in Nixpkgs.</para> + +<para>The lines starting with <literal>#! nix-shell</literal> specify +<command>nix-shell</command> options (see above). Note that you cannot +write <literal>#! /usr/bin/env nix-shell -i ...</literal> because +many operating systems only allow one argument in +<literal>#!</literal> lines.</para> + +<para>For example, here is a Python script that depends on Python and +the <literal>prettytable</literal> package: + +<programlisting> +#! /usr/bin/env nix-shell +#! nix-shell -i python -p python pythonPackages.prettytable + +import prettytable + +# Print a simple table. +t = prettytable.PrettyTable(["N", "N^2"]) +for n in range(1, 10): t.add_row([n, n * n]) +print t +</programlisting> + +</para> + +<para>Similarly, the following is a Perl script that specifies that it +requires Perl and the <literal>HTML::TokeParser::Simple</literal> and +<literal>LWP</literal> packages: + +<programlisting> +#! /usr/bin/env nix-shell +#! nix-shell -i perl -p perl perlPackages.HTMLTokeParserSimple perlPackages.LWP + +use HTML::TokeParser::Simple; + +# Fetch nixos.org and print all hrefs. +my $p = HTML::TokeParser::Simple->new(url => 'http://nixos.org/'); + +while (my $token = $p->get_tag("a")) { + my $href = $token->get_attr("href"); + print "$href\n" if $href; +} +</programlisting> + +</para> + +<para>Finally, the following Haskell script uses a specific branch of +Nixpkgs/NixOS (the 14.12 stable branch): + +<programlisting><![CDATA[ +#! /usr/bin/env nix-shell +#! nix-shell -i runghc -p haskellPackages.ghc haskellPackages.HTTP haskellPackages.tagsoup +#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-14.12.tar.gz + +import Network.HTTP +import Text.HTML.TagSoup + +-- Fetch nixos.org and print all hrefs. +main = do + resp <- Network.HTTP.simpleHTTP (getRequest "http://nixos.org/") + body <- getResponseBody resp + let tags = filter (isTagOpenName "a") $ parseTags body + let tags' = map (fromAttrib "href") tags + mapM_ putStrLn $ filter (/= "") tags' +]]></programlisting> + +If you want to be even more precise, you can specify a specific +revision of Nixpkgs: + +<programlisting> +#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/0672315759b3e15e2121365f067c1c8c56bb4722.tar.gz +</programlisting> + +</para> + +<para>The examples above all used <option>-p</option> to get +dependencies from Nixpkgs. You can also use a Nix expression to build +your own dependencies. For example, the Python example could have been +written as: + +<programlisting> +#! /usr/bin/env nix-shell +#! nix-shell deps.nix -i python +</programlisting> + +where the file <filename>deps.nix</filename> in the same directory +as the <literal>#!</literal>-script contains: + +<programlisting> +with import <nixpkgs> {}; + +runCommand "dummy" { buildInputs = [ python pythonPackages.prettytable ]; } "" +</programlisting> + +</para> + +</refsection> + + +<refsection condition="manpage"><title>Environment variables</title> + +<variablelist> + <xi:include href="env-common.xml#xmlns(db=http://docbook.org/ns/docbook)xpointer(//db:variablelist[@xml:id='env-common']/*)" /> +</variablelist> + +</refsection> + + +</refentry> |