why does this code " npm install -g fauna-shell" give me this error

Question

This is npm error in fauna. I used glitch:

npm ERR! path /opt/nvm/versions/node/v12.0.0/lib/node_modules
npm ERR! > code EACCES
npm ERR! errno -13
npm ERR! syscall access 
npm ERR! Error:
    
> EACCES: permission denied, access
    > '/opt/nvm/versions/node/v12.0.0/lib/node_modules'
 
npm ERR!  [Error:

> EACCES: permission denied, access
    > '/opt/nvm/versions/node/v12.0.0/lib/node_modules'] {
 
npm ERR!   stack:
        > 'Error: EACCES: permission denied, access ' + npm ERR!    
        > "'/opt/nvm/versions/node/v12.0.0/lib/node_modules'", npm ERR!   errno:
        > -13, npm ERR!   code: 'EACCES', npm ERR!   syscall: 'access', npm ERR!   path: '/opt/nvm/versions/node/v12.0.0/lib/node_modules' npm ERR! } npm
        > ERR!  npm ERR! The operation was rejected by your operating system.
        > npm ERR! It is likely you do not have the permissions to access this
        > file as the current user npm ERR!  npm ERR! If you believe this might
        > be a permissions issue, please double-check the npm ERR! permissions
        > of the file and its containing directories, or try running npm ERR!
        > the command again as root/Administrator (though this is not
        > recommended).
        > 
        > npm ERR! A complete log of this run can be found in: npm ERR!    
        > /tmp/npm-cache/12.0.0/_logs/2020-12-26T18_09_35_762Z-debug.log

Answer 1

The user you are running the command has doesn't have install rights to /opt/...