nvm use fails when NVM_DIR ends with a slash

[chrisse27]

• Operating system and version: Linux

• nvm debug output:

nvm --version: v0.33.8
$SHELL: /bin/bash
$HOME: /home/bamboo
$NVM_DIR: '$HOME/.nvm/'
$PREFIX: ''
$NPM_CONFIG_PREFIX: ''
$NVM_NODEJS_ORG_MIRROR: 'https://nodejs.org/dist'
$NVM_IOJS_ORG_MIRROR: 'https://iojs.org/dist'
shell version: 'GNU bash, version 4.3.48(1)-release (x86_64-pc-linux-gnu)'
uname -a: 'Linux 4.4.0-109-generic #132-Ubuntu SMP Tue Jan 9 19:52:39 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux'
OS version: Ubuntu 16.04.3 LTS
curl: /usr/bin/curl, curl 7.47.0 (x86_64-pc-linux-gnu) libcurl/7.47.0 GnuTLS/3.4.10 zlib/1.2.8 libidn/1.32 librtmp/2.3
wget: /usr/bin/wget, GNU Wget 1.17.1 built on linux-gnu.
git: /usr/bin/git, git version 2.7.4
grep: /bin/grep, grep (GNU grep) 2.25
awk: /usr/bin/awk, GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.4, GNU MP 6.1.0)
sed: /bin/sed, sed (GNU sed) 4.2.2
cut: /usr/bin/cut, cut (GNU coreutils) 8.25
basename: /usr/bin/basename, basename (GNU coreutils) 8.25
rm: /bin/rm, rm (GNU coreutils) 8.25
mkdir: /bin/mkdir, mkdir (GNU coreutils) 8.25
xargs: /usr/bin/xargs, xargs (GNU findutils) 4.7.0-git
nvm current: v6.9.1
which node: $NVM_DIR/versions/node/v6.9.1/bin/node
which iojs:
which npm: $NVM_DIR/versions/node/v6.9.1/bin/npm
npm config get prefix: $NVM_DIR/versions/node/v6.9.1
npm root -g: $NVM_DIR/versions/node/v6.9.1/lib/node_modules

• nvm ls output:

• How did you install nvm? (e.g. install script in readme, homebrew):

Install script in readme

• What steps did you perform?

nvm use 9

• What happened?

nvm is not compatible with the npm config "prefix" option: currently set to "/home/bamboo/.nvm/versions/node/v8.9.1"
Run `nvm use --delete-prefix v8.9.1` to unset it.

• What did you expect to happen?

That nvm switches to the new Node version.

This is a bug in the function nvm_tree_contains_path which cannot deal with trailing slashes in the NVM_DIR variable. removing the slash solves the problem. I anyway opened this issue to spare future users hours of painful debugging.

• Is there anything in any of your profile files (.bashrc, .bash_profile, .zshrc, etc) that modifies the PATH?

• If you are having installation issues, or getting "N/A", what does curl -I --compressed -v https://nodejs.org/dist/ print out?

[ljharb]

Hmm, how did the trailing slash end up there in the first place?

[chrisse27]

@ljharb That was a configuration that our Admins were setting up in our Bamboo CI. Of course we had them change that now, but I found it a bit disturbing that a slash in the "wrong" place can do this harm. It's not only the function I mentioned above that has a problem with this. Also calling nvm current starts reporting the wrong version when the NVM_DIR has the trailing slash.

[ljharb]

@chrisse27 would you be interested in submitting a PR that explicitly fails with a helpful error message when a directory path has a trailing slash, in all the places you find, with associated tests?

[ljharb]

(please do note; a slash in the wrong place with mv can do harm too; it's simply the nature of posix that a directory path does not end in a slash; the slash indicates "inside the directory" - your admins should know that)

[chrisse27]

@ljharb I can do that, although we are still discussing among the team whether it's better to educate the users or help them by normalizing the path.

[ljharb]

I think that since the primary use case for nvm is the install script populating NVM_DIR, and users manually providing it is an edge case, that it's more important to educate them.

[chrisse27]

Just had a look at the code. Adding an error message everywhere where NVM_DIR is used is too much of an effort. I will submit an PR for a change in the documentation.

[PeterDaveHello]

Path ends with trailing / isn't that invalid in fact, #1734 can fix it :)

[chrisse27]

Thanks for the fix @PeterDaveHello. I am looking forward to the discussions with @ljharb regarding how valid the trailing slash is.

[PeterDaveHello]

@chrisse27 let me know if it fixes your problem if you have time to test it, thanks :)

[ljharb]

It can be fixed, but no, it's not valid. Try using mv or rm on a directory with a trailing slash and you'll see that it's not :-)

[PeterDaveHello]

Yes, I tested mv with Ubuntu and Alpine, it works perfectly. rm is not for directory but rmdir is, but rm -r also works fine here.

[ljharb]

You may have been trying with the source arg, or with a nonexistent dest arg. Try mv src dest vs mv src dest/ when dest exists.

[PeterDaveHello]

I got what do you mean, still no problem here though.

[ljharb]

In the former example it will replace dest; in the latter it will move src inside dest. That’s because the trailing slash means “inside the dir”, and without the slash it’s “the dir”.

[PeterDaveHello]

Yeah, I know the difference, but in the case of $NVM_DIR, I think we won't have this issue?

[ljharb]

Not at the moment; but that doesn’t change that the proper path to a directory has no trailing slash :-)