Modern Full-Stack Development

 OS  (os)
The OS module provides a set of operating system–level utility functions that allow your 
code to be aware of the environment it’s running in and make any necessary allowances 
for it. Some of what it offers include the following:
•  os.EOL – Provides you the end-of-line character the operating system 
uses
•  os.cpus() – Returns an object array where each object gives you 
information about the CPU(s) in the system including information 
like their model, speed, and times (e.g., how long the CPU has spent 
in user mode)
•  os.freemem() – Returns an integer value that is the number of free 
system memory available in bytes
•  os.homedir() – Returns a path to the current home directory of the 
user running the process
•  os.hostname() – Returns the machine’s host name
•  os.tempdir() – Returns a path to the default system temporary 
directory
You’ll also find an os.constants property that is an object with several keys, things 
like SIGHUP, SIGFPE, SIGCHILD, and SIGSTOP. These are commonly used OS-specific 
constants for things like error codes and, as in these examples, process signals. These 
will, of course, change from system to system to at least some extent, but it’s good to 
know such a collection of information like this exists and is made available to you thanks 
to the OS module!
Chapter 2   a Few More words: advanCed node and npM

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