Recently, I’ve been paying attention to the time it takes my shell’s init script to complete. Bash is notoriously slow, but since it’s popular in scripting use, I keep using it. This leaves me to optimize my ~/.bashrc.

I program with Node.js frequently, so a Node.js version manager is an essential tool. Upon investigating the execution time of my .bashrc, I found that loading nvm takes a lot of time:

$ ls ~/.nvm/versions/node
v10.11.0	v8.12.0		v9.11.2

$ export NVM_DIR="$HOME/.nvm"

$ time source "$HOME/brew/opt/nvm/nvm.sh"

real	0m0.397s
user	0m0.270s
sys	0m0.134s

$ nvm --version
0.33.11

400 ms for sourcing nvm.sh is a way too big share of the time budget I’d like to allocate for starting Bash in interactive mode. It’s a pity, because nvm is a quite nice tool.

An alternative for nvm is nodenv:

$ ls ~/.nodenv/versions
10.11.0	8.12.0	9.11.2

$ time eval "$(~/brew/bin/nodenv init -)"

real	0m0.070s
user	0m0.034s
sys	0m0.034s

$ nodenv --version
nodenv 1.1.2

I can manage with 70 ms. This is the tool I chose to use as my Node.js version manager for a while. But because nodenv utilizes shims to wrap the executables of the selected Node.js version, a couple of problems arise. The first is that after installing a new executable from global npm package, you must remember to run nodenv rehash to rebuild the shims. Otherwise you can’t run the executable. The second is that you lose access to the manual pages of the wrapped executables: a shim is an indirection for the actual executable, causing man’s manual page search to miss the page. A demonstration of the problems:

$ npm ls -g --depth=0
/Users/tkareine/.nodenv/versions/10.11.0/lib
`-- npm@6.4.1

$ npm install -g marked
/Users/tkareine/.nodenv/versions/10.11.0/bin/marked -> /Users/tkareine/.nodenv/versions/10.11.0/lib/node_modules/marked/bin/marked
+ marked@0.5.1
added 1 package from 1 contributor in 0.586s

$ command -v marked

$ nodenv rehash

$ command -v marked
/Users/tkareine/.nodenv/shims/marked

$ man -w node
No manual entry for node

$ man -w marked
No manual entry for marked

I keep forgetting to run nodenv rehash and I do would like to access the manual pages of the executables of the selected Node.js version.

nvm and nodenv have a lot of features. While they are useful in some scenarios, such as continuous integration setups, I’d be satisfied with less in my development environment. The ability to install specific Node.js versions and to switch between them easily, independently per shell session, would be enough.

In the Ruby community, ruby-install and chruby tools provide just these features, and nothing more. The former is for installing Rubies and the latter for switching between them. What’s great about this arrangement of separate tools is that the switcher, chruby, is very lightweight.

node-build, part of nodenv project, is a dedicated Node.js installer. It checks the digest of the downloaded Node.js package and allows you to unpack it to any directory. This is good and I’ll keep using it.

For the version switcher, I didn’t find anything I liked. sh-chnode is written in the same spirit as chruby, but includes some design decisions I didn’t like personally.

I ended up writing my own version switcher, even though there’s already so many of them. But this one is fast to load, does one thing well, and is suitable for me. :) Naming is hard, so I just call it chnode. Let’s see it in action:

$ ls ~/.nodes
node-10.11.0	node-8.12.0	node-9.11.2

$ time source ~/brew/opt/chnode/share/chnode/chnode.sh

real	0m0.007s
user	0m0.004s
sys	0m0.003s

$ chnode node-10

$ chnode
 * node-10.11.0
   node-8.12.0
   node-9.11.2

$ npm ls -g --depth=0
/Users/tkareine/.nodes/node-10.11.0/lib
└── npm@6.4.1

$ command -v marked
/Users/tkareine/.nodes/node-10.11.0/bin/marked

$ man -w node
/Users/tkareine/.nodes/node-10.11.0/share/man/man1/node.1

$ man -w marked
/Users/tkareine/.nodes/node-10.11.0/share/man/man1/marked.1

$ chnode --version
chnode: 0.2.0

For me, chnode is the tool comparable to chruby for Node.js versions. Like chruby, the primary mechanism of chnode is to modify the PATH environment variable to include the path to the bin subdirectory of the selected Node.js version. But unlike chruby, chnode does not modify any Node.js specific environment variable (there’s no need).

I didn’t implement auto-switching to chnode. The feature would switch Node.js version to the version specified in the .node-version file if the current working directory, or its parent, would have the file. You might put such a file at a project’s root directory. chruby has the feature, but because I don’t use it, I dropped it.

chnode supports GNU Bash and Zsh, has good test coverage, and allows you to display the selected Node.js version in the shell prompt with ease. It’s MIT licensed. See the README for more.

Finally, the total execution time of initializing my Bash setup in interactive mode, including selecting a Node.js version with chnode:

$ time bash -i -c true

real	0m0.337s
user	0m0.240s
sys	0m0.083s