When installing packages from npm, you may see the -s flag added to the npm install command as follows:
npm install -s
The -s flag is a shorthand for the silent configuration, which sets the log level of your npm installation process to nothing.
The following Terminal commands are all equal:
npm install -s
npm install --silent
npm install --loglevel silent
When you install npm packages using the -s flag, then npm won’t log any output to the console. You won’t be able to know whether the installation is successful or not from the Terminal.
A regular npm install command will show the following output:
$ npm install react
added 4 packages, and audited 17 packages in 2s
2 packages are looking for funding
run `npm fund` for details
found 0 vulnerabilities
$
While npm install with the -s flag will show no output at all:
$ npm install vue -s
$
To know if your installation is successful, you need to open the package.json file and see if the package name is listed as dependencies.
Alternatively, you can open the node_modules/ folder and check if a folder with the package name exists there.
Keep in mind that the npm command flag is case-sensitive. The lower case -s flag is used to set the log level mode to silent, while the upper case -S flag is used to save installed packages to a package.json file as dependencies.
The npm save configuration has been set to true by default since npm version 5.