nmap -p [port] hostName

## Scan port 80
nmap -p 80 192.168.1.1

## Scan TCP port 80
nmap -p T:80 192.168.1.1

## Scan UDP port 53
nmap -p U:53 192.168.1.1

## Scan two ports ##
nmap -p 80,443 192.168.1.1

## Scan port ranges ##
nmap -p 80-200 192.168.1.1

## Combine all options ##
nmap -p U:53,111,137,T:21-25,80,139,8080 192.168.1.1
nmap -p U:53,111,137,T:21-25,80,139,8080 server1.cyberciti.biz
nmap -v -sU -sT -p U:53,111,137,T:21-25,80,139,8080 192.168.1.254

## Scan all ports with * wildcard ##
nmap -p "*" 192.168.1.1

## Scan top ports i.e. scan $number most common ports ##
nmap --top-ports 5 192.168.1.1
nmap --top-ports 10 192.168.1.1