Remove existing npm folder before copying activated version

[shadowspawn]

Pull Request Template:

Describe what you did

Improve robustness of install of npm included with node (over a previous install).

How you did it

Delete previous npm install folder.

How to verify it doesn't effect the functionality of n

node and npm still functional after activating node versions, issues addressed.

If this solves an issue, please put issue in PR notes.

Issue #440
Issue #453
Issue #462
(And probably issues #206, #236, #403)

If this solves an issue, please include the output of issue that had problems and then the fixed output from the same command.

Notes on reproduce steps:

• assuming default install location for initial rm -rf
• add sudo if required
• cp warnings are a Darwin issue which is also improved
• the forest-arborist install is to show that global modules are not deleted, not otherwise significant

Issue #440. Checked on macOS High Sierra and Debian Jessie.

Before
$ rm -rf /usr/local/lib/node_modules/npm /usr/local/bin/node
$ n 6.11.5
cp: symlink: ../lib/node_modules/npm/bin/npm-cli.js: File exists
$ npm install --global @shadowspawn/forest-arborist
$ n 8.8.1
cp: symlink: ../lib/node_modules/npm/bin/npx-cli.js: File exists
$ npm list --global --depth=0
/usr/local/lib
├── @shadowspawn/[email protected]
└── [email protected]

npm ERR! missing: npm-package-arg@^4.1.1, required by [email protected]
npm ERR! invalid: [email protected] /usr/local/lib/node_modules/npm/node_modules/init-package-json/node_modules/glob
npm ERR! missing: strip-ansi@^3.0.1, required by [email protected]
npm ERR! missing: strip-ansi@^3.0.0, required by [email protected]
npm ERR! invalid: [email protected] /usr/local/lib/node_modules/npm/node_modules/npm-registry-client/node_modules/concat-stream/node_modules/readable-stream
npm ERR! missing: strip-ansi@^3.0.1, required by [email protected]
npm ERR! missing: strip-ansi@^3.0.0, required by [email protected]
npm ERR! invalid: [email protected] /usr/local/lib/node_modules/npm/node_modules/read-package-json/node_modules/glob
npm ERR! missing: strip-ansi@^3.0.0, required by [email protected]

After
$ rm -rf /usr/local/lib/node_modules/npm /usr/local/bin/node
$ n 6.11.5
$ npm install --global @shadowspawn/forest-arborist
$ n 8.8.1
$ npm list --global --depth=0
/usr/local/lib
├── @shadowspawn/[email protected]
└── [email protected]

Issue #453. Checked on macOS High Sierra and Debian Jessie.

Before
$ rm -rf /usr/local/lib/node_modules/npm /usr/local/bin/node
$ n 4.1.2
cp: symlink: ../lib/node_modules/npm/bin/npm-cli.js: File exists
$ n 8.2.1
cp: symlink: ../lib/node_modules/npm/bin/npx-cli.js: File exists
$ npm doctor
npm ERR! code MODULE_NOT_FOUND
npm ERR! Cannot find module 'internal/fs'

npm ERR! A complete log of this run can be found in:
npm ERR! /Users/john/.npm/_logs/2017-10-29T00_49_59_380Z-debug.log

After
$ rm -rf /usr/local/lib/node_modules/npm /usr/local/bin/node
$ n 4.1.2
$ n 8.2.1
$ npm doctor
npm WARN verifyCachedFiles Content garbage-collected: 3 (87960 bytes)
npm WARN verifyCachedFiles Cache issues have been fixed
Check Value Recommendation
npm ping OK
npm -v v5.3.0 Use npm v5.5.1
node -v v8.2.1
npm config get registry https://registry.npmjs.org/
which git /usr/bin/git
Perms check on cached files ok
Perms check on global node_modules ok
Perms check on local node_modules ok
Verify cache contents verified 1345 tarballs

Issue #462

Before
$ rm -rf /usr/local/lib/node_modules/npm /usr/local/bin/node
$ n 5.0.0
cp: symlink: ../lib/node_modules/npm/bin/npm-cli.js: File exists
$ n 7.0.0
$ npm install
npm ERR! Darwin 17.0.0
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "install"
npm ERR! node v7.0.0
npm ERR! npm v3.10.8
npm ERR! code MODULE_NOT_FOUND

npm ERR! Cannot find module 'internal/fs'
npm ERR!
npm ERR! If you need help, you may report this error at:
npm ERR! https://github.com/npm/npm/issues

npm ERR! Please include the following file with any support request:
npm ERR! /Users/john/Documents/Sandpits/ReproduceTemp/npm-debug.log

After (expected error running npm install in empty directory)
$ rm -rf /usr/local/lib/node_modules/npm /usr/local/bin/node
$ n 5.0.0
$ n 7.0.0
$ npm install
npm WARN enoent ENOENT: no such file or directory, open '/Users/john/Documents/Sandpits/ReproduceTemp/package.json'
npm WARN ReproduceTemp No description
npm WARN ReproduceTemp No repository field.
npm WARN ReproduceTemp No README data
npm WARN ReproduceTemp No license field.

Issues #206, #236, #403

Likely to address the described issue by removing previous npm install folder before copy, but unable to reproduce the original problem using the described steps so not confirmed.

Squash any unnecessary commits to keep history clean as possible

Place description for the changelog in PR so we can tally all changes for any future release

Delete old npm folder before copying new folder.

[shadowspawn]

I encountered an error on Mac when cp is overwriting a dangling link. The work-around used here is to copy lib before bin and restore the link. Two other approaches would be to explicitly delete the expected npm and npx links, or scan for broken links about to be overwritten.

[shadowspawn]

Deleting the previous install folder is the same approach used by the nodejs Mac installer:
https://github.com/nodejs/node/blob/master/tools/macos-installer/pkgbuild/npm/scripts/preinstall

[shadowspawn]

Also fixes #472, albeit reproduced and tested on MacOS rather than Ubuntu.

[shadowspawn]

Fixes issue #476, albeit reproduced by starting from node 4.0.0.

[shadowspawn]

Fixes #510. Reproduced and tested on macOS.

[troy0820]

I'm going to try to test this in a container and make sure it doesn't break any older versions.

[troy0820]

Issue #440
Issue #453
Issue #462
(And probably issues #206, #236, #403)

Tested this in a centos container. Deleting the npm folder and then activating the version works. Also solves issue #510 that @iarna described.

Thanks for helping with this issue.

[iamstarkov]

if you installed n through npm and cant install new n version anymore because npm is broken, take a look at this https://github.com/mklement0/n-install#updating-n

[iamstarkov]

I was at node 8

n-update
n prune
n 10
n prune
n lts

this got me working node again