Kill a Process by Looking up the Port being used by it from a .BAT

Open command prompt and run the following commands

 C:\Users\username>netstat -o -n -a | findstr 0.0:3000
   TCP    0.0.0.0:3000      0.0.0.0:0              LISTENING       3116

C:\Users\username>taskkill /F /PID 3116

, here 3116 is the process ID

To find specific process on command line use below command here 8080 is port used by process

netstat -ano | findstr 8080

to kill process use below command here 21424 is process id

taskkill /pid 21424 /F 

Here's a command to get you started:

FOR /F "tokens=4 delims= " %%P IN ('netstat -a -n -o ^| findstr :8080') DO @ECHO TaskKill.exe /PID %%P

When you're confident in your batch file, remove @ECHO.

FOR /F "tokens=4 delims= " %%P IN ('netstat -a -n -o ^| findstr :8080') DO TaskKill.exe /PID %%P

Note that you might need to change this slightly for different OS's. For example, on Windows 7 you might need tokens=5 instead of tokens=4.

How this works

FOR /F ... %variable IN ('command') DO otherCommand %variable...

This lets you execute command, and loop over its output. Each line will be stuffed into %variable, and can be expanded out in otherCommand as many times as you like, wherever you like. %variable in actual use can only have a single-letter name, e.g. %V.

"tokens=4 delims= "

This lets you split up each line by whitespace, and take the 4th chunk in that line, and stuffs it into %variable (in our case, %%P). delims looks empty, but that extra space is actually significant.

netstat -a -n -o

Just run it and find out. According to the command line help, it "Displays all connections and listening ports.", "Displays addresses and port numbers in numerical form.", and "Displays the owning process ID associated with each connection.". I just used these options since someone else suggested it, and it happened to work :)

^|

This takes the output of the first command or program (netstat) and passes it onto a second command program (findstr). If you were using this directly on the command line, instead of inside a command string, you would use | instead of ^|.

findstr :8080

This filters any output that is passed into it, returning only lines that contain :8080.

TaskKill.exe /PID <value>

This kills a running task, using the process ID.

%%P instead of %P

This is required in batch files. If you did this on the command prompt, you would use %P instead.

Using Merlyn's solution caused other applications to be killed like firefox. These processes were using the same port, but not as a listener:

eg:

netstat -a -n -o | findstr :8085
  TCP    0.0.0.0:8085           0.0.0.0:0              LISTENING       6568
  TCP    127.0.0.1:49616        127.0.0.1:8085         TIME_WAIT       0
  TCP    127.0.0.1:49618        127.0.0.1:8085         TIME_WAIT       0

Therefore, can excluded these by adding "LISTENING" to the findstr as follows:

FOR /F "tokens=5 delims= " %%P IN ('netstat -a -n -o ^| findstr :8085.*LISTENING') DO TaskKill.exe /PID %%P