This is a good reference article. Also this.
Print stuff
echo "hello world!"
FS navigation
pwd
cd
cd ..
ls
ls -a
FS manipulation
mkdir
rmdir
touch
rm
rm -rf
cp source destination
mv source destination
chmod
chown
cmp
diff
Reading data from file
head hello.txt
tail hello.txt
cat hello.txt
grep
Open files in default editors
code file_name
edit file_name
OS and networking
ps
kill -9 pid
uname
whoami
sudo
Helpers
clear
exit
man command_name
whereis
whatis
--help
ctrl+c
ctrl+shift+c
ctrl+shift+v
ctrl+alt+t
tab
alias
tar
zip
wget
Git commands
git init
git add .
git commit -m "commit msg"
git status
git clone
git remote add origin origin_url
git remote -v
git log
git pull
git push
git branch
git checkout
git merge
git diff