Note: if you are using sudo for the install, by default the command you run does not have access to your exported environment variables. You can use sudo -E to pass the existing environment variables.
The nvh command downloads and installs to /usr/local by default, but you may override this location by defining NVH_PREFIX. e.g.
export NVH_PREFIX=$HOME/.nvh
export PATH=$NVH_PREFIX/bin:$PATH
NVH_NODE_MIRROR: overrides default https://nodejs.org/dist/NVH_NODE_DOWNLOAD_MIRROR: overrides default https://nodejs.org/download
If the custom mirror requires basic authentication, you can url-encode the username and password directly in the URL:
export NVH_NODE_MIRROR='https://user:password@host/path'
Note: the username and password will be visible (via ps) to other users on your computer while a download is running.
nvh ls-remote defaults to a showing a maximum of 20 matching versions, but you can change this. e.g.
export NVH_MAX_REMOTE_MATCHES=3
By default the node install also includes npm and npx. You can change this by setting NVH_PRESERVE_NPM to a non-empty string. This has the same affect as specifying --preserve on the command line, and leaves npm and npx out of the install preserving the current versions.
export NVH_PRESERVE_NPM=1
You can be explicit to get the desired behaviour whatever the environment variable:
nvh install --no-preserve latest
nvh install --preserve nightly
See also https_proxy in Proxy Server.