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12 <h1><a href="../files/npm-folders.html">npm-folders</a></h1> <p>Folder Structures Used by npm</p>
13 <h2 id="description">DESCRIPTION</h2>
14 <p>npm puts various things on your computer. That's its job.</p>
15 <p>This document will tell you what it puts where.</p>
16 <h3 id="tl-dr">tl;dr</h3>
18 <li>Local install (default): puts stuff in <code>./node_modules</code> of the current
20 <li>Global install (with <code>-g</code>): puts stuff in /usr/local or wherever node
22 <li>Install it <strong>locally</strong> if you're going to <code>require()</code> it.</li>
23 <li>Install it <strong>globally</strong> if you're going to run it on the command line.</li>
24 <li>If you need both, then install it in both places, or use <code>npm link</code>.</li>
26 <h3 id="prefix-configuration">prefix Configuration</h3>
27 <p>The <code>prefix</code> config defaults to the location where node is installed.
28 On most systems, this is <code>/usr/local</code>. On windows, this is the exact
29 location of the node.exe binary. On Unix systems, it's one level up,
30 since node is typically installed at <code>{prefix}/bin/node</code> rather than
31 <code>{prefix}/node.exe</code>.</p>
32 <p>When the <code>global</code> flag is set, npm installs things into this prefix.
33 When it is not set, it uses the root of the current package, or the
34 current working directory if not in a package already.</p>
35 <h3 id="node-modules">Node Modules</h3>
36 <p>Packages are dropped into the <code>node_modules</code> folder under the <code>prefix</code>.
37 When installing locally, this means that you can
38 <code>require("packagename")</code> to load its main module, or
39 <code>require("packagename/lib/path/to/sub/module")</code> to load other modules.</p>
40 <p>Global installs on Unix systems go to <code>{prefix}/lib/node_modules</code>.
41 Global installs on Windows go to <code>{prefix}/node_modules</code> (that is, no
42 <code>lib</code> folder.)</p>
43 <p>Scoped packages are installed the same way, except they are grouped together
44 in a sub-folder of the relevant <code>node_modules</code> folder with the name of that
45 scope prefix by the @ symbol, e.g. <code>npm install @myorg/package</code> would place
46 the package in <code>{prefix}/node_modules/@myorg/package</code>. See <code><a href="../misc/scope.html">scope(7)</a></code> for
48 <p>If you wish to <code>require()</code> a package, then install it locally.</p>
49 <h3 id="executables">Executables</h3>
50 <p>When in global mode, executables are linked into <code>{prefix}/bin</code> on Unix,
51 or directly into <code>{prefix}</code> on Windows.</p>
52 <p>When in local mode, executables are linked into
53 <code>./node_modules/.bin</code> so that they can be made available to scripts run
54 through npm. (For example, so that a test runner will be in the path
55 when you run <code>npm test</code>.)</p>
56 <h3 id="man-pages">Man Pages</h3>
57 <p>When in global mode, man pages are linked into <code>{prefix}/share/man</code>.</p>
58 <p>When in local mode, man pages are not installed.</p>
59 <p>Man pages are not installed on Windows systems.</p>
60 <h3 id="cache">Cache</h3>
61 <p>See <code><a href="../cli/npm-cache.html">npm-cache(1)</a></code>. Cache files are stored in <code>~/.npm</code> on Posix, or
62 <code>~/npm-cache</code> on Windows.</p>
63 <p>This is controlled by the <code>cache</code> configuration param.</p>
64 <h3 id="temp-files">Temp Files</h3>
65 <p>Temporary files are stored by default in the folder specified by the
66 <code>tmp</code> config, which defaults to the TMPDIR, TMP, or TEMP environment
67 variables, or <code>/tmp</code> on Unix and <code>c:\windows\temp</code> on Windows.</p>
68 <p>Temp files are given a unique folder under this root for each run of the
69 program, and are deleted upon successful exit.</p>
70 <h2 id="more-information">More Information</h2>
71 <p>When installing locally, npm first tries to find an appropriate
72 <code>prefix</code> folder. This is so that <code>npm install foo@1.2.3</code> will install
73 to the sensible root of your package, even if you happen to have <code>cd</code>ed
74 into some other folder.</p>
75 <p>Starting at the $PWD, npm will walk up the folder tree checking for a
76 folder that contains either a <code>package.json</code> file, or a <code>node_modules</code>
77 folder. If such a thing is found, then that is treated as the effective
78 "current directory" for the purpose of running npm commands. (This
79 behavior is inspired by and similar to git's .git-folder seeking
80 logic when running git commands in a working dir.)</p>
81 <p>If no package root is found, then the current folder is used.</p>
82 <p>When you run <code>npm install foo@1.2.3</code>, then the package is loaded into
83 the cache, and then unpacked into <code>./node_modules/foo</code>. Then, any of
84 foo's dependencies are similarly unpacked into
85 <code>./node_modules/foo/node_modules/...</code>.</p>
86 <p>Any bin files are symlinked to <code>./node_modules/.bin/</code>, so that they may
87 be found by npm scripts when necessary.</p>
88 <h3 id="global-installation">Global Installation</h3>
89 <p>If the <code>global</code> configuration is set to true, then npm will
90 install packages "globally".</p>
91 <p>For global installation, packages are installed roughly the same way,
92 but using the folders described above.</p>
93 <h3 id="cycles-conflicts-and-folder-parsimony">Cycles, Conflicts, and Folder Parsimony</h3>
94 <p>Cycles are handled using the property of node's module system that it
95 walks up the directories looking for <code>node_modules</code> folders. So, at every
96 stage, if a package is already installed in an ancestor <code>node_modules</code>
97 folder, then it is not installed at the current location.</p>
98 <p>Consider the case above, where <code>foo -> bar -> baz</code>. Imagine if, in
99 addition to that, baz depended on bar, so you'd have:
100 <code>foo -> bar -> baz -> bar -> baz ...</code>. However, since the folder
101 structure is: <code>foo/node_modules/bar/node_modules/baz</code>, there's no need to
102 put another copy of bar into <code>.../baz/node_modules</code>, since when it calls
103 require("bar"), it will get the copy that is installed in
104 <code>foo/node_modules/bar</code>.</p>
105 <p>This shortcut is only used if the exact same
106 version would be installed in multiple nested <code>node_modules</code> folders. It
107 is still possible to have <code>a/node_modules/b/node_modules/a</code> if the two
108 "a" packages are different versions. However, without repeating the
109 exact same package multiple times, an infinite regress will always be
111 <p>Another optimization can be made by installing dependencies at the
112 highest level possible, below the localized "target" folder.</p>
113 <h4 id="example">Example</h4>
114 <p>Consider this dependency graph:</p>
118 | +-- blerg@1.x (latest=1.3.7)
121 | | `-- bar@1.2.3 (cycle)
126 </code></pre><p>In this case, we might expect a folder structure like this:</p>
129 +-- blerg (1.2.5) <---[A]
130 +-- bar (1.2.3) <---[B]
132 | +-- baz (2.0.2) <---[C]
136 `-- baz (1.2.3) <---[D]
138 `-- quux (3.2.0) <---[E]
139 </code></pre><p>Since foo depends directly on <code>bar@1.2.3</code> and <code>baz@1.2.3</code>, those are
140 installed in foo's <code>node_modules</code> folder.</p>
141 <p>Even though the latest copy of blerg is 1.3.7, foo has a specific
142 dependency on version 1.2.5. So, that gets installed at [A]. Since the
143 parent installation of blerg satisfies bar's dependency on <code>blerg@1.x</code>,
144 it does not install another copy under [B].</p>
145 <p>Bar [B] also has dependencies on baz and asdf, so those are installed in
146 bar's <code>node_modules</code> folder. Because it depends on <code>baz@2.x</code>, it cannot
147 re-use the <code>baz@1.2.3</code> installed in the parent <code>node_modules</code> folder [D],
148 and must install its own copy [C].</p>
149 <p>Underneath bar, the <code>baz -> quux -> bar</code> dependency creates a cycle.
150 However, because bar is already in quux's ancestry [B], it does not
151 unpack another copy of bar into that folder.</p>
152 <p>Underneath <code>foo -> baz</code> [D], quux's [E] folder tree is empty, because its
153 dependency on bar is satisfied by the parent folder copy installed at [B].</p>
154 <p>For a graphical breakdown of what is installed where, use <code>npm ls</code>.</p>
155 <h3 id="publishing">Publishing</h3>
156 <p>Upon publishing, npm will look in the <code>node_modules</code> folder. If any of
157 the items there are not in the <code>bundledDependencies</code> array, then they will
158 not be included in the package tarball.</p>
159 <p>This allows a package maintainer to install all of their dependencies
160 (and dev dependencies) locally, but only re-publish those items that
161 cannot be found elsewhere. See <code><a href="../files/package.json.html">package.json(5)</a></code> for more information.</p>
162 <h2 id="see-also">SEE ALSO</h2>
164 <li><a href="../misc/npm-faq.html">npm-faq(7)</a></li>
165 <li><a href="../files/package.json.html">package.json(5)</a></li>
166 <li><a href="../cli/npm-install.html">npm-install(1)</a></li>
167 <li><a href="../cli/npm-pack.html">npm-pack(1)</a></li>
168 <li><a href="../cli/npm-cache.html">npm-cache(1)</a></li>
169 <li><a href="../cli/npm-config.html">npm-config(1)</a></li>
170 <li><a href="../files/npmrc.html">npmrc(5)</a></li>
171 <li><a href="../misc/npm-config.html">npm-config(7)</a></li>
172 <li><a href="../cli/npm-publish.html">npm-publish(1)</a></li>
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186 <p id="footer">npm-folders — npm@2.15.11</p>
Code Review / simantics / district.git / blob