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authorErlang/OTP <[email protected]>2009-11-20 14:54:40 +0000
committerErlang/OTP <[email protected]>2009-11-20 14:54:40 +0000
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The R13B03 release.OTP_R13B03
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+<?xml version="1.0" encoding="latin1" ?>
+<!DOCTYPE fileref SYSTEM "fileref.dtd">
+
+<fileref>
+ <header>
+ <copyright>
+ <year>1997</year>
+ <year>2007</year>
+ <holder>Ericsson AB, All Rights Reserved</holder>
+ </copyright>
+ <legalnotice>
+ The contents of this file are subject to the Erlang Public License,
+ Version 1.1, (the "License"); you may not use this file except in
+ compliance with the License. You should have received a copy of the
+ Erlang Public License along with this software. If not, it can be
+ retrieved online at http://www.erlang.org/.
+
+ Software distributed under the License is distributed on an "AS IS"
+ basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ the License for the specific language governing rights and limitations
+ under the License.
+
+ The Initial Developer of the Original Code is Ericsson AB.
+ </legalnotice>
+
+ <title>script</title>
+ <prepared>Martin Bj&ouml;rklund</prepared>
+ <responsible>Bjarne D&auml;cker</responsible>
+ <docno></docno>
+ <approved>Bjarne D&auml;cker</approved>
+ <checked></checked>
+ <date>97-06-03</date>
+ <rev>A</rev>
+ <file>script.sgml</file>
+ </header>
+ <file>script</file>
+ <filesummary>Boot script</filesummary>
+ <description>
+ <p>The <em>boot script</em> describes how the Erlang runtime system is
+ started. It contains instructions on which code to load and
+ which processes and applications to start.
+ </p>
+ <p>The command <c>erl -boot Name</c> starts the system with a boot
+ file called <c>Name.boot</c>, which is generated from the
+ <c>Name.script</c> file, using <c>systools:script2boot/1</c>.
+ </p>
+ <p>The <c>.script</c> file is generated by <c>systools</c> from a
+ <c>.rel</c> file and <c>.app</c> files.
+ </p>
+ </description>
+
+ <section>
+ <title>FILE SYNTAX</title>
+ <p>The boot script is stored in a file with the extension
+ <c>.script</c></p>
+ <p>The file has the following syntax:
+ </p>
+ <code type="none">
+{script, {Name, Vsn},
+ [
+ {progress, loading},
+ {preLoaded, [Mod1, Mod2, ...]},
+ {path, [Dir1,"$ROOT/Dir",...]}.
+ {primLoad, [Mod1, Mod2, ...]},
+ ...
+ {kernel_load_completed},
+ {progress, loaded},
+ {kernelProcess, Name, {Mod, Func, Args}},
+ ...
+ {apply, {Mod, Func, Args}},
+ ...
+ {progress, started}]}. </code>
+ <list type="bulleted">
+ <item><c>Name = string()</c> defines the name of the system.
+ </item>
+ <item><c>Vsn = string()</c> defines the version of the system.
+ </item>
+ <item><c>{progress, Term}</c> sets the "progress" of the
+ initialization program. The function <c>init:get_status()</c>
+ returns the current value of the progress, which is
+ <c>{InternalStatus,Term}</c>.
+ </item>
+ <item>
+ <p><c>{path, [Dir]}</c> where <c>Dir</c> is a string. This
+ argument sets the load path of the system to <c>[Dir]</c>. The
+ load path used to load modules is obtained from the initial
+ load path, which is given in the script file, together with
+ any path flags which were supplied in the command line
+ arguments. The command line arguments modify the path as
+ follows:</p>
+ <list type="bulleted">
+ <item><c>-pa Dir1 Dir2 ... DirN</c> adds the directories
+ <c>Dir1, Dir2, ..., DirN</c> to the front of the initial
+ load path.
+ </item>
+ <item><c>-pz Dir1 Dir2 ... DirN</c> adds the directories
+ <c>Dir1, Dir2, ..., DirN</c> to the end of the initial
+ load path.
+ </item>
+ <item>
+ <p><c>-path Dir1 Dir2 ... DirN</c> defines a set of
+ directories <c>Dir1, Dir2, ..., DirN</c> which replaces
+ the search path given in the script file. Directory names
+ in the path are interpreted as follows:</p>
+ <list type="bulleted">
+ <item>Directory names starting with <c>/</c> are assumed
+ to be absolute path names.
+ </item>
+ <item>Directory names not starting with <c>/</c> are
+ assumed to be relative the current working directory.
+ </item>
+ <item>The special <c>$ROOT</c> variable can only be used
+ in the script, not as a command line argument. The
+ given directory is relative the Erlang installation
+ directory.
+ </item>
+ </list>
+ </item>
+ </list>
+ </item>
+ <item><c>{primLoad, [Mod]}</c> loads the modules <c>[Mod]</c>
+ from the directories specified in <c>Path</c>. The script
+ interpreter fetches the appropriate module by calling the
+ function <c>erl_prim_loader:get_file(Mod)</c>. A fatal error
+ which terminates the system will occur if the module cannot be
+ located.
+ </item>
+ <item><c>{kernel_load_completed}</c> indicates that all modules
+ which <em>must</em> be loaded <em>before</em> any processes
+ are started are loaded. In interactive mode, all
+ <c>{primLoad,[Mod]}</c> commands interpreted after this
+ command are ignored, and these modules are loaded on demand.
+ In embedded mode, <c>kernel_load_completed</c> is ignored, and
+ all modules are loaded during system start.
+ </item>
+ <item><c>{kernelProcess, Name, {Mod, Func, Args}}</c> starts a
+ "kernel process". The kernel process <c>Name</c> is started
+ by evaluating <c>apply(Mod, Func, Args)</c> which is expected
+ to return <c>{ok, Pid}</c> or <c>ignore</c>. The <c>init</c>
+ process monitors the behaviour of <c>Pid</c> and terminates
+ the system if <c>Pid</c> dies. Kernel processes are key
+ components of the runtime system. Users do not normally add
+ new kernel processes.
+ </item>
+ <item><c>{apply, {Mod, Func, Args}}</c>. The init process simply
+ evaluates <c>apply(Mod, Func, Args)</c>. The system
+ terminates if this results in an error. The boot procedure
+ hangs if this function never returns.
+ </item>
+ </list>
+ <note>
+ <p>In the <c>interactive</c> system the code loader provides
+ demand driven code loading, but in the <c>embedded</c> system
+ the code loader loads all the code immediately. The same
+ version of <c>code</c> is used in both cases. The code server
+ calls <c>init:get_argument(mode)</c> to find out if it should
+ run in demand mode, or non-demand driven mode.
+ </p>
+ </note>
+ </section>
+
+ <section>
+ <title>SEE ALSO</title>
+ <p>systools(3)
+ </p>
+ </section>
+</fileref>
+