Since I connect my server to SSH to do couple of tweaks and modifications, It’s important for you to know what all commands are available and what all it could do for you while you execute it especially if your going to manage a server through SSH. Therefore, I have given a list of basic SSH commands in CentOS which I use while I manage servers.

ls – list the contents of the current directory
ls -a – list the contents of the current directory including hidden files)]
ls -l – shows you file permissions and ownership
cd – change directory
cp – copy
scp – secure copy
chmod – change permissions
chown – change the owner of a file
/ – top level directory
Tab key – autocomplete words
grep – search file
wc – count characters/words/lines
up arrow – shows your previous commands
mkdir (directory name) – make a new directory with the name given
rm -R (directory name) – delete directory
cd ../ – move up a directory in the file system (parent directory)
touch (filename) – create file
nano (filename) – create file using nano command line text editor
cat – view the contents of a text file.
more – view the contents of a text file, allows you to view by page (spacebar to move to the next page)
rm (filename) – delete file
rm *.(filetype) – delete all files of a specified type
rmdir – remove directory
yum update – updates the package cache
^ – symbol is Ctrl (called the caret)
Ctrl + C – cancels the command
wget (Link to file) – downloads the file from internet
sudo logout – logout (only needs sudo if a non root user)
sudo reboot – reboot server (only needs sudo if a non root user)
su – logs in as root if already logged in as a non root user

You may also read Monitor Usage in Linux Server too for additional commands.