1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">
<erlref>
<header>
<copyright>
<year>1996</year><year>2016</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
</legalnotice>
<title>erl_prim_loader</title>
<prepared></prepared>
<docno></docno>
<date></date>
<rev></rev>
<file>erl_prim_loader.xml</file>
</header>
<module>erl_prim_loader</module>
<modulesummary>Low Level Erlang Loader</modulesummary>
<description>
<p><c>erl_prim_loader</c> is used to load all Erlang modules into
the system. The start script is also fetched with this low level
loader.</p>
<p><c>erl_prim_loader</c> knows about the environment and how to
fetch modules.</p>
<p>The <c>-loader Loader</c> command line flag can be used to
choose the method used by the <c>erl_prim_loader</c>. Two
<c>Loader</c> methods are supported by the Erlang runtime system:
<c>efile</c> and <c>inet</c>.</p>
<warning><p>The support for loading of code from archive files is
experimental. The sole purpose of releasing it before it is ready
is to obtain early feedback. The file format, semantics,
interfaces etc. may be changed in a future release. The functions
<c>list_dir/1</c> and <c>read_file_info/1</c> as well as the flag
<c>-loader_debug</c> are also experimental</p></warning>
</description>
<funcs>
<func>
<name name="get_file" arity="1"/>
<fsummary>Get a file</fsummary>
<desc>
<p>This function fetches a file using the low level loader.
<c><anno>Filename</anno></c> is either an absolute file name or just the name
of the file, for example <c>"lists.beam"</c>. If an internal
path is set to the loader, this path is used to find the file.
<c><anno>FullName</anno></c> is the complete name of the fetched file.
<c><anno>Bin</anno></c> is the contents of the file as a binary.</p>
<p>The <c><anno>Filename</anno></c> can also be a file in an archive. For example
<c>$OTPROOT/lib/</c><c>mnesia-4.4.7.ez/mnesia-4.4.7/ebin/</c><c>mnesia.beam</c>.
See <seealso marker="kernel:code">code(3)</seealso> about archive files.</p>
</desc>
</func>
<func>
<name name="get_path" arity="0"/>
<fsummary>Get the path set in the loader</fsummary>
<desc>
<p>This function gets the path set in the loader. The path is
set by the <c>init</c> process according to information found
in the start script.</p>
</desc>
</func>
<func>
<name name="list_dir" arity="1"/>
<fsummary>List files in a directory</fsummary>
<desc>
<p>Lists all the files in a directory. Returns
<c>{ok, <anno>Filenames</anno>}</c> if successful. Otherwise, it returns
<c>error</c>. <c><anno>Filenames</anno></c> is a list of
the names of all the files in the directory. The names are
not sorted.</p>
<p>The <c><anno>Dir</anno></c> can also be a directory in an archive. For example
<c>$OTPROOT/lib/</c><c>mnesia-4.4.7.ez/mnesia-4.4.7/ebin</c>.
See <seealso marker="kernel:code">code(3)</seealso> about archive files.</p>
</desc>
</func>
<func>
<name name="read_file_info" arity="1"/>
<fsummary>Get information about a file</fsummary>
<desc>
<p>Retrieves information about a file. Returns
<c>{ok, <anno>FileInfo</anno>}</c> if successful, otherwise
<c>error</c>. <c><anno>FileInfo</anno></c> is a record
<c>file_info</c>, defined in the Kernel include file
<c>file.hrl</c>. Include the following directive in the module
from which the function is called:</p>
<code type="none">
-include_lib("kernel/include/file.hrl").</code>
<p>See <seealso marker="kernel:file">file(3)</seealso> for more info about
the record <c>file_info</c>.</p>
<p>The <c><anno>Filename</anno></c> can also be a file in an archive. For example
<c>$OTPROOT/lib/</c><c>mnesia-4.4.7.ez/mnesia-4.4.7/ebin/</c><c>mnesia</c>.
See <seealso marker="kernel:code">code(3)</seealso> about archive files.</p>
</desc>
</func>
<func>
<name name="read_link_info" arity="1"/>
<fsummary>Get information about a link or file</fsummary>
<desc>
<p>This function works like
<seealso marker="#read_file_info/1">read_file_info/1</seealso>
except that if <c><anno>Filename</anno></c> is a symbolic link,
information about the link will be returned in the <c>file_info</c>
record and the <c>type</c> field of the record will be set to
<c>symlink</c>.</p>
<p>If <c><anno>Filename</anno></c> is not a symbolic link, this function
returns exactly the same result as <c>read_file_info/1</c>.
On platforms that do not support symbolic links, this function
is always equivalent to <c>read_file_info/1</c>.</p>
</desc>
</func>
<func>
<name name="set_path" arity="1"/>
<fsummary>Set the path of the loader</fsummary>
<desc>
<p>This function sets the path of the loader if <c>init</c>
interprets a <c>path</c> command in the start script.</p>
</desc>
</func>
</funcs>
<section>
<title>Command Line Flags</title>
<p>The <c>erl_prim_loader</c> module interprets the following
command line flags:</p>
<taglist>
<tag><c>-loader Loader</c></tag>
<item>
<p>Specifies the name of the loader used by
<c>erl_prim_loader</c>. <c>Loader</c> can be <c>efile</c>
(use the local file system) or <c>inet</c> (load using
the <c>boot_server</c> on another Erlang node).</p>
<p>If the <c>-loader</c> flag is omitted, it defaults to
<c>efile</c>.</p>
</item>
<tag><c>-loader_debug</c></tag>
<item>
<p>Makes the <c>efile</c> loader write some debug information,
such as the reason for failures, while it handles files.</p>
</item>
<tag><c>-hosts Hosts</c></tag>
<item>
<p>Specifies which other Erlang nodes the <c>inet</c> loader
can use. This flag is mandatory if the <c>-loader inet</c>
flag is present. On each host, there must be on Erlang node
with the <seealso
marker="kernel:erl_boot_server">erl_boot_server(3)</seealso>
which handles the load requests.
<c>Hosts</c> is a list of IP addresses (hostnames
are not acceptable).</p>
</item>
<tag><c>-setcookie Cookie</c></tag>
<item>
<p>Specifies the cookie of the Erlang runtime system. This flag
is mandatory if the <c>-loader inet</c> flag is present.</p>
</item>
</taglist>
</section>
<section>
<title>SEE ALSO</title>
<p><seealso marker="init">init(3)</seealso>,
<seealso marker="kernel:erl_boot_server">erl_boot_server(3)</seealso></p>
</section>
</erlref>
|
