Important Commands of Linux operating System

help  - This command will show you the basic linux commands and the it's usage
man - it will show the manual of software or program or service
Like run :
man node

The about command will show the manual of using the program
mkdir - creare folder / directory
cd - go into directoru
pwd - will show current path
ls - will show current folder files
cp - copy file 
mv - rename or move the file
rm - delete the file or folder
sudo su - get root privilage
cat - show file content
nano - file Editor 
gedir - file editor
chmod - file permission
chown - file user
bash - run file
apt-get update - update repos / or apps new paths (it will not update software but get the software update info)
apt-get upgrade - update all tools
apt-get update gedit 

gedit is software, update specific software