"which nvm" is gone

Question

I installed NVM on an ubuntu machine, but, when I put it in the crontab for execution during reboot:

@reboot nvm use 0; 

it didn't work, and I got a mail from the cron daemon, saying:

/bin/sh: 1: nvm: not found

So, I thought this a path problem, and tried to find where NVM is installed. To my surprise, I got empty results:

root@vps-1145280-18735:~# which nvm
root@vps-1145280-18735:~# 

But, NVM itself does work, even after reboot:

root@vps-1145280-18735:~# nvm

Node Version Manager
...

This is very strange - how can it be that the system finds the nvm program, when the "which nvm" is empty?!

And, more important - what should I do in order to have the cron program find NVM during startup?

Answer 1

The nvm command is not a file but rather a shell function.

The source ~/.nvm/nvm.sh adds these functions to your current shell. And because these commands are not files, they don't show up when you which nvm.

Looking in the .nvm/nvm.sh file, you can see a nvm() {...} function defined that provides that functionality.

Cron is likely using as different user, and that user needs to have source ~/.nvm/nvm.sh added to its shell context before running.