Main Partitions in Linux
1)  “ / ”  à /  is the main partition of Linux , All the file
and folders ( with O/s ) will be installed in this / only. Without / it is not
possible to install O/s.
2)   /boot à /boot
is necessary to keep MBR ( Master Boot Record ) file to load the O/s in RAM.
3)  /swap à It is a virtual memory of Linux. It is recommended to give the size
of  /swap 
should be double of RAM.
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To use the Redhat or Centos7 in CLI
(Command Line Interface ) we need a terminal (By Default available)