sh:1:节点:权限被拒绝

试图在ubuntu 18.04上运行这个命令

npm install -g pngquant-bin

[..................] | fetchMetadata: sill resolveWithNewModule npm-conf@1.1.3 checking installable status
npm WARN deprecated gulp-util@3.0.8: gulp-util is deprecated - replace it, following the guidelines at https://medium.com/gulpjs/gulp-util-ca3b1f9f9ac5
/root/.nvm/versions/node/v10.8.0/bin/pngquant -> /root/.nvm/versions/node/v10.8.0/lib/node_modules/pngquant-bin/cli.js

> pngquant-bin@5.0.0 postinstall /root/.nvm/versions/node/v10.8.0/lib/node_modules/pngquant-bin
> node lib/install.js

sh: 1: node: Permission denied
npm ERR! file sh
npm ERR! code ELIFECYCLE
npm ERR! errno ENOENT
npm ERR! syscall spawn
npm ERR! pngquant-bin@5.0.0 postinstall: `node lib/install.js`
npm ERR! spawn ENOENT
npm ERR!
npm ERR! Failed at the pngquant-bin@5.0.0 postinstall script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /root/.npm/_logs/2018-08-12T18_08_02_197Z-debug.log

你知道怎么处理这个吗? articles 但没有成功。