The way to run emulator from console (I assume that you installed it before, using Android Studio) is:

run cd ~/Android/Sdk/tools/bin && ./avdmanager list avd

You will get the list od your virtual installed devices. In my case it was:

Available Android Virtual Devices:
 Name: Galaxy_Nexus_API_17
 Device: Galaxy Nexus (Google)
 Path: /home/piotr/.android/avd/Galaxy_Nexus_API_17.avd
 Target: Google APIs (Google Inc.)
 Based on: Android 4.2 (Jelly Bean) Tag/ABI: google_apis/x86
 Skin: galaxy_nexus
 Sdcard: /home/piotr/.android/avd/Galaxy_Nexus_API_17.avd/sdcard.img
---------
 Name: Nexus_5X_API_23
 Device: Nexus 5X (Google)
 Path: /home/piotr/.android/avd/Nexus_5X_API_23.avd
 Target: Google APIs (Google Inc.)
 Based on: Android 6.0 (Marshmallow) Tag/ABI: google_apis/x86
 Skin: nexus_5x
 Sdcard: /home/piotr/.android/avd/Nexus_5X_API_23.avd/sdcard.img

Copy name of device you want to run and then

cd ~/Android/Sdk/tools && ./emulator -avd NAME_OF_YOUR_DEVICE

in my case:

cd ~/Android/Sdk/tools && ./emulator -avd Nexus_5X_API_23

On MacOS

First list down the installed emulators

~/Library/Android/sdk/tools/emulator -list-avds

then run an emulator

~/Library/Android/sdk/tools/emulator -avd Nexus_5X_API_27

Try this

1. Complete Video tutorials (For all windows versions)

OR

2. Text tutorials

• Open the command prompt and change the directory where your sdk is placed D:SoftwaresAndroidsdktoolsbin>
  


• now add your avdmanager in this,now your full code is D:SoftwaresAndroidsdktoolsbin>avdmanager list avd
  


• it will show you a list of emulator device that you have already created after few seconds


• now typecd..
  


• 
  

  and run your emulator with this cmd, Here my emulator name is Tablet_API_25 so I have typed this name after the -avd.

  
  
  

  D:SoftwaresAndroidsdktools>emulator -avd Tablet_API_25

  
  

In the ANDROID_HOME folder you will have tools folder

In Mac/Linux

emulator -avd <avdName>

In Windows

emulator.exe -avd <avdName>


If you are using API 24 You can get the names of the emulator from the list

android list avds

If you are using API 25 then you will get it with avdmanager in toolsbin

avdmanager list avds


You can make a batch file, that will open your emulator directly without opening Android Studio. If you are using Windows:

• Open Notepad




• New file



• 
  

  Copy the next lines into your file:

  
  
  

  C:/
  cd C:Users%username%AppDataLocalAndroidsdktools
  emulator @[YOUR_EMULATOR_DEVICE_NAME]
  

  
  
  

  Notes:

  
  
  

  • Replace [YOUR_EMULATOR_DEVICE_NAME] with the device name you created in emulator

  
  

  • To get the device name go to: C:Users%username%AppDataLocalAndroidsdktools

  
  

  • Run cmd and type: emulator -list-avds

  
  

  • Copy the device name and paste it in the batch file

  
  



• Save the file as emulator.bat and close




• Now double click on emulator.bat and you got the emulator running!

to list the emulators you have

~/Library/Android/sdk/tools/emulator -list-avds

for example, I have this Nexus_5X_API_24

so the command to run that emulator is

cd ~/Library/Android/Sdk/tools && ./emulator -avd Nexus_5X_API_24

Here’s what you need to do:

1.Download and extract the SDK.
2.Open a terminal and navigate to the “tools” directory.
3.Launch the “android” tool (./android if you are currently in the tools directory).
4.Tick off the “SDK Platform” for each version of Android that you’d like to use in your emulator.
5.Click the “Install N Packages” button.
6.Click each package and tick off “Accept License” (legally, I’m probably required to tell you that this step may take several hours as you read each license ;).
7.Done with those licenses? Great. Click “Install”. Wait for the SDK manager to finish installing your packages, then you can close it.
8.Back in your terminal, still in the tools directory, enter ./android avd which will launch the Android Virtual Device Manager.
9.Click “New” and fill out the form to build the device you’d like to emulate. In the “Target” dropdown, you’ll see the SDK Platforms that you installed earlier. If the version you need is missing, you need to go back and install it. Click OK when you’re done.
10.Click on the device that you just created and click the “Start” button, tweak any options that you need on the Launch Options window, and click “Launch”.

Check this question's answer also.

Assuming you have installed Android studio properly,Open a command prompt and type
emulator -list-avds which will display all the devices and then type emulator @avd_name where avd_name is the the name of your emulator installed.

Firstly change the directory where your avd devices are listed; for me it is here:

cd ~/Android/Sdk/tools

Then run the emulator by following command:
./emulator -avd Your_avd_device_name

For me it is:

./emulator -avd Nexus_5X_API_27

That's all.

I already have the Studio installed. But without starting (not installing) the Android Studio you can directly start the emulator with

C:UsersYOURUSERNAMEAppDataLocalAndroidSdktoolsemulator.exe -netdelay none -netspeed full -avd YOUR_AVD_NAME

The path for emulator is

/Users/<Username>/AppData/Local/Android/sdk/tools

Assuming you've got Android Studio installed, and SDK in your PATH, it's:

emulator -avd avd_name

To get a list of AVD names, run:

emulator -list-avds

Source: https://developer.android.com/studio/run/emulator-commandline.html

For Linux/Ubuntu

Create a new File from Terminal as

gedit emulator.sh (Use any Name for file here i have used "emulator")

now write following lines in this file

cd /home/userName/Android/Sdk/tools/

./emulator @your created Android device Name

(here after @ write the name of your AVD e.g

./emulator @Nexus_5X_API_27
)

Now save the file and run your emulator using following commands

./emulator.sh

In case of Permission denied use following command before above command

chmod +x emulator.sh

All set Go..

Got it working for Windows 10:

C:UsersUserNameAppDataLocalAndroidSdktools>emulator -list-avds
Nexus_5X_API_28
C:UsersUserNameAppDataLocalAndroidSdkemulator>emulator -avd Nexus_5X_API_28

This is the commands on Mac

cd ~/Library/Android/Sdk/tools/bin && ./avdmanager list avd

then

cd ~/Library/Android/Sdk/tools && ./emulator -avd NAME_OF_YOUR_DEVICE

if you installed Git on your system. then you can run .sh bash code. I create the bash code for search from your created ADV Devices and list them. then you can select the number of adv device for run emulator without running Android studio.

link:
adv-emulator.sh

note [windows os]: please first add %appdata%..LocalAndroidSdkemulator to your system Environment path, otherwise the bash-code not work.

On windows

......Androidsdktoolsbinavdmanager list avds

......Androidsdktoolsemulator.exe -avd Nexus_5X_API_27

I am working with a React Native project and I also faced this problem

I solved it by making a .bat file in my desktop that I can open fast

The content of the .bat is

C:UsershariaAppDataLocalAndroidsdkemulatoremulator -avd Pixel_2_XL_API_27

Where haria is my Windows username and
Pixel_2_XL_API_27 is my emulator name

If you want to see your emulator name, open CMD (or PowerShell) and type (In Windows)

cd C:UsershariaAppDataLocalAndroidsdkemulator

Then to see the emulator(s) name

./emulator -list-avds

For Windows

In case anyone looking for shortcut / batch script - Gist - Download batch file.

@echo off
IF [%1]== (GOTO ExitWithPrompt)
set i=1
FOR /F "delims=" %%i IN ('emulator -list-avds') DO (
 set /A i=i+1
 set em=%%i
 if %i% == %1 (
 echo Starting %em%
 emulator -avd %em%
 EXIT /B 0
 )
)
GOTO :Exit
:ExitWithPrompt
emulator -list-avds
echo Please enter the emulator number to start

:Exit
EXIT /B 0

Usage

D:>start-emulator
Nexus_5_API_26
Please enter the emulator number to start

D:>start-emulator 1
Starting Nexus_5_API_26
HAX is working and emulator runs in fast virt mode.

(Only for Windows)
Why to torture yourself? Make a Simple BAT file ! :

1. Open Notepad


2. Create the command as shown below


3. Save as *.bat


4. (Optional) Create a shortcut to that *.bat, rename shortcut and change icon

Here is the command:

cd /d yourSdkPathemulator && emulator -avd yourAVDName

Example:

cd /d D:Android_SDKemulator && emulator -avd Nexus_5_API_28

If you are on windows, what about a shortcut ? It is very easy to place whatever you want ant the icon is descriptive and nice.

• First, navigate to your android sdk, probably at C:UsersYOURUSERNAMEAppDataLocalAndroidSdktools
  


• Then right click on emulator.exe and then click create shortcut.


• Your new and shiny shortcut gets created, probably with a predefined name.


• Right click on the shortcut, and on the target field (my computer is on spanish) add an extra parameter with the name of your device with an @ in front (take a look at the picture below )

now you can do whatever yhou want with that shortcut, put on the desktop, bind it to the start-menu or whatever