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authorEelco Dolstra <eelco.dolstra@logicblox.com>2015-02-17T13·42+0100
committerEelco Dolstra <eelco.dolstra@logicblox.com>2015-02-17T13·42+0100
commita70d275f3d25f6e1eb1b6d528ee07ecd7265ada5 (patch)
treea103bd4348be410ec66dbde0551ec3ad5d442a74 /doc/manual
parent29e1ff675b6b8f1ba2cdcde599888ec3eebce9af (diff)
Allow passing attributes via files instead of environment variables
Closes #473.
Diffstat (limited to 'doc/manual')
-rw-r--r--doc/manual/expressions/advanced-attributes.xml21
1 files changed, 21 insertions, 0 deletions
diff --git a/doc/manual/expressions/advanced-attributes.xml b/doc/manual/expressions/advanced-attributes.xml
index 274e36f5c1d0..fee35f0bef48 100644
--- a/doc/manual/expressions/advanced-attributes.xml
+++ b/doc/manual/expressions/advanced-attributes.xml
@@ -242,6 +242,27 @@ stdenv.mkDerivation {
   </varlistentry>
 
 
+  <varlistentry><term><varname>passAsFile</varname></term>
+
+    <listitem><para>A list of names of attributes that should be
+    passed via files rather than environment variables.  For example,
+    if you have
+
+    <programlisting>
+passAsFile = ["big"];
+big = "a very long string";
+    </programlisting>
+
+    then when the builder runs, the environment variable
+    <envar>big</envar> will contain the absolute path to a temporary
+    file containing <literal>a very long string</literal>. This is
+    useful when you need to pass large strings to a builder, since
+    most operating systems impose a limit on the size of the
+    environment (typically, a few hundred kilobyte).</para></listitem>
+
+  </varlistentry>
+
+
   <varlistentry><term><varname>preferLocalBuild</varname></term>
 
     <listitem><para>If this attribute is set to