node/deps/npm/man/man1/install.1

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.\" http://github.com/kapouer/ronnjs/
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.TH "NPM\-INSTALL" "1" "January 2012" "" ""
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.SH "NAME"
\fBnpm-install\fR \-\- Install a package
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.SH "SYNOPSIS"
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.nf
npm install (with no args in a package dir)
npm install <tarball file>
npm install <tarball url>
npm install <folder>
npm install <name>
npm install <name>@<tag>
npm install <name>@<version>
npm install <name>@<version range>
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.fi
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.SH "DESCRIPTION"
This command installs a package, and any packages that it depends on\.
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.P
A \fBpackage\fR is:
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a) a folder containing a program described by a package\.json file
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b) a gzipped tarball containing (a)
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c) a url that resolves to (b)
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d) a \fB<name>@<version>\fR that is published on the registry with (c)
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e) a \fB<name>@<tag>\fR that points to (d)
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f) a \fB<name>\fR that has a "latest" tag satisfying (e)
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g) a \fB<git remote url>\fR that resolves to (b)
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.P
Even if you never publish your package, you can still get a lot of
benefits of using npm if you just want to write a node program (a), and
perhaps if you also want to be able to easily install it elsewhere
after packing it up into a tarball (b)\.
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\fBnpm install\fR (in package directory, no arguments):
Install the dependencies in the local node_modules folder\.
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In global mode (ie, with \fB\-g\fR or \fB\-\-global\fR appended to the command),
it installs the current package context (ie, the current working
directory) as a global package\.
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\fBnpm install <folder>\fR:
Install a package that is sitting in a folder on the filesystem\.
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\fBnpm install <tarball file>\fR:
Install a package that is sitting on the filesystem\.  Note: if you just want
to link a dev directory into your npm root, you can do this more easily by
using \fBnpm link\fR\|\.
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.IP
Example:
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.nf
npm install \./package\.tgz
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.fi
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\fBnpm install <tarball url>\fR:
Fetch the tarball url, and then install it\.  In order to distinguish between
this and other options, the argument must start with "http://" or "https://"
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.IP
Example:
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.nf
npm install https://github\.com/indexzero/forever/tarball/v0\.5\.6
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.fi
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\fBnpm install <name>\fR:
Do a \fB<name>@<tag>\fR install, where \fB<tag>\fR is the "tag" config\. (See \fBnpm help config\fR)
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.IP
Example:
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.nf
npm install sax
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.fi
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.IP
\fBNote\fR: If there is a file or folder named \fB<name>\fR in the current
working directory, then it will try to install that, and only try to
fetch the package by name if it is not valid\.
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\fBnpm install <name>@<tag>\fR:
Install the version of the package that is referenced by the specified tag\.
If the tag does not exist in the registry data for that package, then this
will fail\.
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.IP
Example:
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.nf
npm install sax@latest
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.fi
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\fBnpm install <name>@<version>\fR:
Install the specified version of the package\.  This will fail if the version
has not been published to the registry\.
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.IP
Example:
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.nf
npm install sax@0\.1\.1
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.fi
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\fBnpm install <name>@<version range>\fR:
Install a version of the package matching the specified version range\.  This
will follow the same rules for resolving dependencies described in \fBnpm help json\fR\|\.
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.IP
Note that most version ranges must be put in quotes so that your shell will
treat it as a single argument\.
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.IP
Example:
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.IP "" 4
.
.nf
npm install sax@">=0\.1\.0 <0\.2\.0"
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.fi
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\fBnpm install <git remote url>\fR:
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.IP
Install a package by cloning a git remote url\.  The format of the git
url is:
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.nf
<protocol>://[<user>@]<hostname><separator><path>[#<commit\-ish>]
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.fi
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.IP
\fB<protocol>\fR is one of \fBgit\fR, \fBgit+ssh\fR, \fBgit+http\fR, or \fBgit+https\fR\|\.  If no \fB<commit\-ish>\fR is specified, then \fBmaster\fR is
used\.
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.IP
Examples:
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.nf
git+ssh://git@github\.com:isaacs/npm\.git#v1\.0\.27
git+https://isaacs@github\.com/isaacs/npm\.git
git://github\.com/isaacs/npm\.git#v1\.0\.27
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.fi
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.P
You may combine multiple arguments, and even multiple types of arguments\.
For example:
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.nf
npm install sax@">=0\.1\.0 <0\.2\.0" bench supervisor
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.fi
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.P
The \fB\-\-tag\fR argument will apply to all of the specified install targets\.
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.P
The \fB\-\-force\fR argument will force npm to fetch remote resources even if a
local copy exists on disk\.
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.nf
npm install sax \-\-force
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.fi
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.P
The \fB\-\-global\fR argument will cause npm to install the package globally
rather than locally\.  See \fBnpm help global\fR\|\.
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.P
The \fB\-\-link\fR argument will cause npm to link global installs into the
local space in some cases\.
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.P
See \fBnpm help config\fR\|\.  Many of the configuration params have some
effect on installation, since that\'s most of what npm does\.
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.SH "ALGORITHM"
To install a package, npm uses the following algorithm:
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.nf
install(where, what, family, ancestors)
fetch what, unpack to <where>/node_modules/<what>
for each dep in what\.dependencies
  resolve dep to precise version
for each dep@version in what\.dependencies
    not in <where>/node_modules/<what>/node_modules/*
    and not in <family>
  add precise version deps to <family>
  install(<where>/node_modules/<what>, dep, family)
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.fi
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.P
For this \fBpackage{dep}\fR structure: \fBA{B,C}, B{C}, C{D}\fR,
this algorithm produces:
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.nf
A
+\-\- B
`\-\- C
    `\-\- D
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.fi
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.P
That is, the dependency from B to C is satisfied by the fact that A
already caused C to be installed at a higher level\.
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.P
See npm help folders for a more detailed description of the specific
folder structures that npm creates\.
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.SS "Limitations of npm\'s Install Algorithm"
There are some very rare and pathological edge\-cases where a cycle can
cause npm to try to install a never\-ending tree of packages\.  Here is
the simplest case:
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.nf
A \-> B \-> A\' \-> B\' \-> A \-> B \-> A\' \-> B\' \-> A \-> \.\.\.
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.fi
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.P
where \fBA\fR is some version of a package, and \fBA\'\fR is a different version
of the same package\.  Because \fBB\fR depends on a different version of \fBA\fR
than the one that is already in the tree, it must install a separate
copy\.  The same is true of \fBA\'\fR, which must install \fBB\'\fR\|\.  Because \fBB\'\fR
depends on the original version of \fBA\fR, which has been overridden, the
cycle falls into infinite regress\.
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.P
To avoid this situation, npm flat\-out refuses to install any \fBname@version\fR that is already present anywhere in the tree of package
folder ancestors\.  A more correct, but more complex, solution would be
to symlink the existing version into the new location\.  If this ever
affects a real use\-case, it will be investigated\.
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.SH "SEE ALSO"
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npm help folders
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npm help update
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npm help link
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npm help rebuild
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npm help scripts
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npm help build
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npm help config
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npm help registry
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npm help folders
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npm help tag
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npm help rm
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