How can I call "nvm use" in a bash script, and have the selected node version retained after the script executes?

Question

For a build process that requires updating from Node.js 12 to 14, I'd like a bash script to detect whether nvm is installed, and, if so, do nvm use v14 (or nvm install v14 if necessary), and then I want the nvm-selected node version to stick at 14 after the bash script terminates, not just for the duration of the script.

I can switch to v14 with this script, but after the script has terminated, the shell environment remains at v12:

#!/bin/bash

export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"
[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"
source ~/.bashrc

nvm --version
echo $NVM_BIN
node --version
nvm use v14
echo $NVM_BIN
node --version

Just executing the nvm command in a bash script is a pain because nvm isn't a true command, but a shell function, and the script has to use the first three lines to set up nvm for the script.

The output is:

0.33.11
/home/pi/.nvm/versions/node/v12.21.0/bin
v12.21.0
Now using node v14.16.0 (npm v6.14.11)
/home/pi/.nvm/versions/node/v14.16.0/bin
v14.16.0

When the script is finished, however:

I think the trick might be making sure the environment variable NVM_BIN persists at the v14 path when the script exits, but I don't know how to do that. In fact, I think it's generally not allowed for the shell in which a script executes to change environment variables in the parent shell.

The nvm commmand, however, is itself a shell script, and whatever it does is persistent after it's done executing. There should be some way for me to make this happen too.

pritam · Accepted Answer · 2021-02-25 16:30:20Z

0

I think if you set an alias with nvm for default,

nvm alias default 14.0.0

the node version will persist across any new terminal instances.

answered Feb 25, 2021 at 16:30

pritam

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4 Comments

kshetline Over a year ago

Looked good for a moment there... but sadly, it didn't work.

kshetline Over a year ago

Well... maybe. If I close the terminal I was in, and open the terminal again, then the new default kicks in. That might be good enough, as long as another process started up from the main script inherits this change too, without exiting the original terminal. You at least deserve an up-vote for at least getting me part way. :)

pritam Over a year ago

You can probably try the options mentioned here - stackoverflow.com/questions/47190861/…

Skyrocker Over a year ago

Not sure, why this was marked as a solution, but it's definitely not addressing the core of the problem. I'm also wondering how to call the nvm instance of the terminal which invoked the script, and persist the changed node version particularly in that instance. Updating the system-wide value for every new instance - not an option

Jorge Tovar · Accepted Answer · 2022-09-16 18:28:10Z

0

To have the selected node version after the script executes you can run it like this:

. change-node-version.sh

script

node --version
nvm use 14.18.0
node --version

then:

node --version
➜  v14.18.0

answered Sep 16, 2022 at 18:28

Jorge Tovar

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1 Comment

mwm Over a year ago

Try this: nvm use 6.17.1; change-node-version.sh; node -v. Is it on 14 or 6? My problem is it persisting inside the shell call and not outside. I'm calling it from php exec() and it seems the shell has its context isolated.

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