Ubuntu Manpage: npm-install - Install a package

NAME

       npm-install - Install a package

SYNOPSIS

       npm install (with no args, in package dir)
       npm install [<@scope>/]<name>
       npm install [<@scope>/]<name>@<tag>
       npm install [<@scope>/]<name>@<version>
       npm install [<@scope>/]<name>@<version range>
       npm install <tarball file>
       npm install <tarball url>
       npm install <folder>

       alias: npm i
       common options: [-S|--save|-D|--save-dev|-O|--save-optional] [-E|--save-exact] [--dry-run]

DESCRIPTION

       This command installs a package, and any packages that it depends on. If the package has a
       shrinkwrap file, the installation of dependencies will be driven by  that.  See  npm  help
       shrinkwrap.

       A package is:

       •   a) a folder containing a program described by a npm help 5 package.json file

       •   b) a gzipped tarball containing (a)

       •   c) a url that resolves to (b)

       •   d)  a <name>@<version> that is published on the registry (see npm help 7 npm-registry)
           with (c)

       •   e) a <name>@<tag> that points to (d)

       •   f) a <name> that has a "latest" tag satisfying (e)

       •   g) a <git remote url> that resolves to (a)

       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).

       •   npm install (in package directory, no arguments):

           Install the dependencies in the local node_modules folder.

           In global mode (ie, with -g or --global appended to  the  command),  it  installs  the
           current package context (ie, the current working directory) as a global package.

           By  default, npm install will install all modules listed as dependencies in npm help 5
           package.json.

           With the --production flag (or when  the  NODE_ENV  environment  variable  is  set  to
           production), npm will not install modules listed in devDependencies.

       •   npm install <folder>:

           Install a package that is sitting in a folder on the filesystem.

       •   npm install <tarball file>:

           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 npm link.

           Example:

               npm install ./package.tgz

       •   npm install <tarball url>:

           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://"

           Example:

               npm install https://github.com/indexzero/forever/tarball/v0.5.6

       •   npm install [<@scope>/]<name> [-S|--save|-D|--save-dev|-O|--save-optional]:

           Do  a  <name>@<tag>  install,  where  <tag>  is  the  "tag"  config.  (See  npm help 7
           npm-config.)

           In most cases, this will install the latest version of the module published on npm.

           Example:

               npm install sax

       npm install takes 3 exclusive, optional flags which save or update the package version  in
       your main package.json:

       •   -S, --save: Package will appear in your dependencies.

       •   -D, --save-dev: Package will appear in your devDependencies.

       •   -O, --save-optional: Package will appear in your optionalDependencies.

       When using any of the above options to save dependencies to your package.json, there is an
       additional, optional flag:

       •   -E, --save-exact: Saved dependencies will be configured with an exact  version  rather
           than using npm´s default semver range operator.

       Further, if you have an npm-shrinkwrap.json then it will be updated as well.

       <scope>  is optional. The package will be downloaded from the registry associated with the
       specified scope. If no registry is associated with the given scope the default registry is
       assumed. See npm help 7 npm-scope.

       Note:  if you do not include the @-symbol on your scope name, npm will interpret this as a
       GitHub repository instead, see below. Scopes names must also be followed by a slash.

       Examples:

               npm install sax --save
               npm install githubname/reponame
               npm install @myorg/privatepackage
               npm install node-tap --save-dev
               npm install dtrace-provider --save-optional
               npm install readable-stream --save --save-exact

       Note: If there is a file or folder named <name> 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.

       •   npm install [<@scope>/]<name>@<tag>:

           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.

           Example:

               npm install sax@latest
               npm install @myorg/mypackage@latest

       •   npm install [<@scope>/]<name>@<version>:

           Install the specified version of the package. This will fail if the  version  has  not
           been published to the registry.

           Example:

               npm install sax@0.1.1
               npm install @myorg/privatepackage@1.5.0

       •   npm install [<@scope>/]<name>@<version range>:

           Install  a  version  of  the  package  matching the specified version range. This will
           follow the same rules for resolving dependencies described in npm help 5 package.json.

           Note that most version ranges must be put in quotes so that your shell will  treat  it
           as a single argument.

           Example:

               npm install sax@">=0.1.0 <0.2.0"
               npm install @myorg/privatepackage@">=0.1.0 <0.2.0"

       •   npm install <git remote url>:

           Installs the package from the hosted git provider, cloning it with git. First it tries
           via the https (git with github) and if that fails, via ssh.

               <protocol>://[<user>[:<password>]@]<hostname>[:<port>][:][/]<path>[#<commit-ish>]

       <protocol> is one  of  git,  git+ssh,  git+http,  or  git+https.  If  no  <commit-ish>  is
       specified, then master is used.

       The  following  git  environment  variables are recognized by npm and will be added to the
       environment when running git:

       •   GIT_ASKPASS

       •   GIT_PROXY_COMMAND

       •   GIT_SSH

       •   GIT_SSH_COMMAND

       •   GIT_SSL_CAINFO

       •   GIT_SSL_NO_VERIFY

       See the git man page for details.

       Examples:

               npm install git+ssh://git@github.com:npm/npm.git#v1.0.27
               npm install git+https://isaacs@github.com/npm/npm.git
               npm install git://github.com/npm/npm.git#v1.0.27
               GIT_SSH_COMMAND=´ssh -i ~/.ssh/custom_ident´ npm install git+ssh://git@github.com:npm/npm.git

       •   npm install <githubname>/<githubrepo>[#<commit-ish>]:

       •   npm install github:<githubname>/<githubrepo>[#<commit-ish>]:

           Install the package at https://github.com/githubname/githubrepo by attempting to clone
           it using git.

           If you don´t specify a commit-ish then master will be used.

           Examples:

               npm install mygithubuser/myproject
               npm install github:mygithubuser/myproject

       •   npm install gist:[<githubname>/]<gistID>[#<commit-ish>]:

           Install  the package at https://gist.github.com/gistID by attempting to clone it using
           git. The GitHub username associated with the gist is optional and will not be saved in
           package.json if -S or --save is used.

           If you don´t specify a commit-ish then master will be used.

           Example:

               npm install gist:101a11beef

       •   npm install bitbucket:<bitbucketname>/<bitbucketrepo>[#<commit-ish>]:

           Install the package at https://bitbucket.org/bitbucketname/bitbucketrepo by attempting
           to clone it using git.

           If you don´t specify a commit-ish then master will be used.

           Example:

               npm install bitbucket:mybitbucketuser/myproject

       •   npm install gitlab:<gitlabname>/<gitlabrepo>[#<commit-ish>]:

           Install the package at https://gitlab.com/gitlabname/gitlabrepo by attempting to clone
           it using git.

           If you don´t specify a commit-ish then master will be used.

           Example:

               npm install gitlab:mygitlabuser/myproject

       You may combine multiple arguments, and even multiple types of arguments. For example:

           npm install sax@">=0.1.0 <0.2.0" bench supervisor

       The  --tag  argument will apply to all of the specified install targets. If a tag with the
       given name exists, the tagged version is preferred over newer versions.

       The --dry-run argument will report in the usual way  what  the  install  would  have  done
       without actually installing anything.

       The  -f  or --force argument will force npm to fetch remote resources even if a local copy
       exists on disk.

           npm install sax --force

       The -g or --global argument will cause npm to install the  package  globally  rather  than
       locally. See npm help 5 npm-folders.

       The  --global-style  argument  will  cause  npm  to  install  the  package into your local
       node_modules folder with the same layout it uses with the global node_modules folder. Only
       your  direct  dependencies will show in node_modules and everything they depend on will be
       flattened in their node_modules folders. This obviously will elminate some deduping.

       The --legacy-bundling argument will cause npm to install the package such that versions of
       npm  prior  to  1.4, such as the one included with node 0.8, can install the package. This
       eliminates all automatic deduping.

       The --link argument will cause npm to link global installs into the local  space  in  some
       cases.

       The  --no-bin-links  argument will prevent npm from creating symlinks for any binaries the
       package might contain.

       The --no-optional argument will prevent optional dependencies from being installed.

       The --no-shrinkwrap argument, which will ignore an available shrinkwrap file and  use  the
       package.json instead.

       The --nodedir=/path/to/node/source argument will allow npm to find the node source code so
       that npm can compile native modules.

       The --only={prod[uction]|dev[elopment]} argument will cause either only devDependencies or
       only non-devDependencies to be installed regardless of the NODE_ENV.

       See  npm  help  7  npm-config.  Many  of  the  configuration  params  have  some effect on
       installation, since that´s most of what npm does.

ALGORITHM

To install a package, npm uses the following algorithm:

load the existing node_modules tree from disk
clone the tree
fetch the package.json and assorted metadata and add it to the clone
walk the clone and add any missing dependencies
dependencies will be added as close to the top as is possible
without breaking any other modules
compare the original tree with the cloned tree and make a list of
actions to take to convert one to the other
execute all of the actions, deepest first
kinds of actions are install, update, remove and move

For this package{dep} structure: A{B,C}, B{C}, C{D}, this algorithm produces:

A
+-- B
+-- C
+-- D

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. D is still installed at the top level because nothing
conflicts with it.

For A{B,C}, B{C,D@1}, C{D@2}, this algorithm produces:

A
+-- B
+-- C
`-- D@2
+-- D@1

Because B´s D@1 will be installed in the top level, C now has to install D@2 privately for
itself.

See npm help 5 folders for a more detailed description of the specific folder structures
that npm creates.

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:

A -> B -> A´ -> B´ -> A -> B -> A´ -> B´ -> A -> ...

where A is some version of a package, and A´ is a different version of the same package.
Because B depends on a different version of A than the one that is already in the tree, it
must install a separate copy. The same is true of A´, which must install B´. Because B´
depends on the original version of A, which has been overridden, the cycle falls into
infinite regress.

To avoid this situation, npm flat-out refuses to install any name@version 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.

NAME

SYNOPSIS

DESCRIPTION

ALGORITHM

SEE ALSO