Command

A command is a request to perform an operation or run a program.

You can add a flag which affect how a command can work.

;: - Execute commands in series

echo -n "hello " ; echo "world"
hello world

&&: - Conditionally on success

cat / && echo "world"
cat: /: Is a directory
cd ~/slides/ && du -sh Makefile
4.0K  Makefile

||: - Conditionally on failure

cat / || echo "Cat failed"
cat /: Is a directory
Cat failed
echo -n "hello" || echo "world"
hello