This is really old, but still helpful

1. Basic scan:
   
   $ sudo nmap 192.168.1.50

   1	$ sudo nmap 192.168.1.50

   
    
2. Scan multiple addresses:
   
   $ sudo nmap 192.168.1.50 192.168.1.51 192.168.1.52

   1	$ sudo nmap 192.168.1.50 192.168.1.51 192.168.1.52

   
    
3. Scan entire subnet looking for valid hosts. This quick scan will also grab MAC address and perform MAC lookup to help determine what the host is.
   
   $ sudo nmap -sP 192.168.1.50

   1	$ sudo nmap -sP 192.168.1.50

   
    
4.   Discovery:  Before a scan nmap will attempt to send an ICMP echo request.  To not send the ICMP, :
   
   $ sudo nmap -PN 192.168.1.50

   1	$ sudo nmap -PN 192.168.1.50

   
    
5. To do only a ping scan:
   
   $ sudo nmap -sP 192.168.1.50

   1	$ sudo nmap -sP 192.168.1.50

   
    
6. Do an ARP Ping scan:
   
   $ sudo nmap -PR 192.168.1.50

   1	$ sudo nmap -PR 192.168.1.50

   
    
7. Port Scanning options:  Performing a Fast scan:
   
   $ sudo nmap -F 192.168.1.50

   1	$ sudo nmap -F 192.168.1.50

   
    
8. Scan only specific ports:
   
   $ sudo nmap -p22 192.168.1.50

   1	$ sudo nmap -p22 192.168.1.50

   
    
9. Scan multiple ports:
   
   $ sudo nmap -p 22,25,53 , 80-250 192.168.1.50

   1	$ sudo nmap -p 22,25,53 , 80-250 192.168.1.50

   
    
10. Scan ports by name (found in /etc/services)
    
    $ sudo nmap -p snmtp,ftp  192.168.1.50

    1	$ sudo nmap -p snmtp,ftp  192.168.1.50

    
     
11. Scan all ports:
    
    $ sudo nmap -p "*" 192.168.1.50

    1	$ sudo nmap -p "*" 192.168.1.50

    
     
12. Choose between TCP and/or UDP:
    
    $ sudo nmap -p -T:3000-4000 192.168.1.50

    1	$ sudo nmap -p -T:3000-4000 192.168.1.50

    
     
13. What OS is the target running?
    
    $ sudo nmap -O 192.168.1.50

    1	$ sudo nmap -O 192.168.1.50

    
     
14. If the OS is unknown, have nmap attempt to guess the OS
    
    $ sudo nmap -O --osscan-guess  192.168.1.50

    1	$ sudo nmap -O --osscan-guess  192.168.1.50

    
     
15. Service version detection
    
    $ sudo nmap -sV 192.168.1.50

    1	$ sudo nmap -sV 192.168.1.50

    
     

Here’s a quick method to identify hosts on a subnet.  Also quickly gives some other useful info such as MAC Address and the Company Code for that MAC address.  Whether host is up or down and the latency.

$ sudo nmap -sP 192.168.100.0/24

example

Nmap scan report for 192.168.1.128
Host is up (0.021s latency).
MAC Address: 00:80:77:95:32:19 (Brother Industries)
Nmap scan report for 192.168.1.129
Host is up (0.0052s latency).
MAC Address: 00:0D:4B:D2:BF:30 (Roku)
Nmap scan report for 192.168.1.130
Host is up (0.023s latency).
MAC Address: 00:0D:4B:9A:AA:81 (Roku)