In this blog I'll walk you through on how to config your various terminal to dynamically switch JDK version in a painless? and a bit cooler way right from your terminal. ## Table Of Contents * [Prepare JDK and prerequisites](#prepare-jdk-and-prerequisites) * [Command Prompt](#command-prompt) * [Powershell 5 & 7](#powershell-5-amp-7) * [Cmder](#cmder) --- > why not use the wsl? yes, we can config it easily like we did in any bash in linux, which is cool 😁 and another great thing I found out recently about WSL is that it can execute windows binary file like those `exe` directly from wsl terminal. Don't believe me? here's an example 😜 > I'll test on `oc` cli that I'm using to do stuff with my openshift cluster as an example in this case. - let's start with check where the `oc.exe` is located ![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/avr2nxd5uwffmcbdlmqj.png) - test some command ![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/yd66i00938vbjh9u3dpy.png) - now switch to ubuntu wsl terminal and notice the `oc` bin that belong to this ubuntu wsl ![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/gywvplwwvdkf0afhvli7.png) - let's test some command, we will noticed the `unauth` response since I didn't share the config between windows/wsl ![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/a0yzh7m74bsni8i4eky8.png) - now let's `cd` into the windows folder with the `exe` file we want to test, in order to access our windows file, the path will have to be pre-fix with `/mnt/` and followed by normal drive letter without colon symbol > for example: /mnt/c/windows/system32/ ![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/h4s0c3tijtsjnxzpcgcy.png) - when call the `oc.exe` file we'll notice the response returned normally instead of `unauth` like the above command, this because we invoked the one that belong in windows env which is the same as we invoked in windows `cmd`, amazing isn't it? ![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/qzkzho3aow1qm8i7pgdg.png) --- ok but that's not the point of this blog, if you're like me who don't like context-switching too much and only use it when neccessery, let's continue see what we can do to run multiple JDK in windows env. --- ## 🤖 Prepare JDK and pre-requisites usually when we installed JDK package through windows installer we'll ended up with something like this ![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/u9wy9q4j8jxxtke4ilyb.png) and when we run the java version check it'll run one of these 3 depends on how you installed it, notice that I didn't set the `JAVA_HOME` yet ![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/7uw1w1rlc54gpgi5ualq.png) next, you'll need [chocolatey](https://docs.chocolatey.org/en-us/choco/setup#install-with-cmd.exe) package manager for its `refreshenv` utility, if you don't want to install chocolatey or other reason, you can get this util directly from [chocolatey github](https://github.com/chocolatey/choco/blob/1.1.0/src/chocolatey.resources/redirects/RefreshEnv.cmd) then register the `bat` in `PATH` environment variable and that's it for preparation part. ## 💻 Command Prompt in order to do `alias` or other custom command, we'll have to go extra miles(or Km) to config this `ol-cmd` terminal(seriously, please replace it with something powerful Microsoft 😗) - Choose the location to store our new script files, in this case I'll use `cmd_script` in my `%userprofile%` to store it

create new folder to use as script location

--- - add it to the `PATH` by going to environment variable settings

---

---

look for `PATH` then edit it to add our script location we created earlier

--- - create new folder named `alias` inside the script folder then add it to the `PATH`

--- - create new script called `usejdk.cmd` or `usejdk.bat`

> the above process should be the same when you add `refreshEnv.cmd` if you didn't use chocolatey --- - add the following script to the `usejdk` bat file ```shell @echo off set JDK_VERSION=%~1 if "%JDK_VERSION%" == "" ( goto usage ) else if "%JDK_VERSION%" == "8" ( set JAVA_HOME="C:\Program Files\Eclipse Adoptium\jdk-8.0.345.1-hotspot" ) GOTO :eof :usage ECHO Please select your Java Version ECHO Usage: useJDK [version] EXIT /B 1 ``` > change the JAVA_HOME path to suit your need and add addtional condition if you have more than 2 JDK - Test the script if it's working correctly ```shell C:\Users\Rujra>usejdk 11 C:\Users\Rujra>echo %JAVA_HOME% "C:\Program Files\Eclipse Adoptium\jdk-11.0.16.101-hotspot" C:\Users\Rujra>java -version openjdk version "1.8.0_345" OpenJDK Runtime Environment (Temurin)(build 1.8.0_345-b01) OpenJDK 64-Bit Server VM (Temurin)(build 25.345-b01, mixed mode) C:\Users\Rujra> ``` > noticed that even though we set the `JAVA_HOME` the java runtime didn't changed, that's because it's registered in `PATH` env, hardcoded.

the hard-coded path env that we didn't touch earlier

--- - this can be solve in 2 ways 1. remove the jdk/bin path from our `PATH` env then add a new one with `%JAVA_HOME%\bin` 2. leave it be but move those down to the bottom of `PATH` env then add the java home from `1.` and move it up to the top - this method can be useful if you want to run something like `where java` which will list all knows java binary in `PATH`

--- - let's try again ```shell C:\Users\Rujra>usejdk 11 C:\Users\Rujra>echo %JAVA_HOME% "C:\Program Files\Eclipse Adoptium\jdk-11.0.16.101-hotspot" C:\Users\Rujra>java -version openjdk version "1.8.0_345" OpenJDK Runtime Environment (Temurin)(build 1.8.0_345-b01) OpenJDK 64-Bit Server VM (Temurin)(build 25.345-b01, mixed mode) ``` > still not working 😾 - now let's check the `PATH` ```shell C:\Users\Rujra>PATH PATH=C:\Program Files\WindowsApps\Microsoft.WindowsTerminal_1.14.2282.0_x64__8wekyb3d8bbwe;%JAVA_HOME%\bin;[other path env blah blah blah]; ``` > noticed the %JAVA_HOME% in PATH? that's where our `refreshenv` will come into play next - modify the `usejdk` script with our long-awaited `refreshenv` util ```shell ... ) else if "%JDK_VERSION%" == "8" ( set JAVA_HOME="C:\Program Files\Eclipse Adoptium\jdk-8.0.345.1-hotspot" refreshenv ) ... ``` - third?? time's a charm, I hope 😗. ```shell C:\Users\Rujra>usejdk 11 Refreshing environment variables from registry for cmd.exe. Please wait...Finished.. C:\Users\Rujra>PATH PATH="C:\Program Files\Eclipse Adoptium\jdk-11.0.16.101-hotspot"\bin;[other path env blah blah blah]; C:\Users\Rujra>java -version openjdk version "11.0.16.1" 2022-08-12 OpenJDK Runtime Environment Temurin-11.0.16.1+1 (build 11.0.16.1+1) OpenJDK 64-Bit Server VM Temurin-11.0.16.1+1 (build 11.0.16.1+1, mixed mode) ``` > now it's working, WOW, so easy! 🤯 I almost had a migraine tbh🤷‍♂️. --- ## 💠 Powershell 5 & 7 In powershell, it's a bit easier to manipulate the env var/alias since everything is stored inside "special" `env:` and `alias:` PSdrive > why is it matters? because we will use these to help us switch between multiple JDK in a moment > ! important: before we proceed please make sure you have set the `PATH` variable with `%JAVA_HOME%\bin` at the top like we did in `CMD` steps #### Environment Variable to display the current env we can do the following ```shell PS C:\Users\Rujra> dir env: Name Value ---- ----- ALLUSERSPROFILE C:\ProgramData ChocolateyInstall C:\ProgramData\chocolatey ``` > to query specific key, just add the key to path `dir env:\some_thing` > to query value only, add `$` to env `$env:some_thing` --- #### Alias to display Alias is the same as Env var ```shell PS C:\Users\Rujra> dir alias: CommandType Name Version Source ----------- ---- ------- ------ Alias % -> ForEach-Object Alias ? -> Where-Object Alias CFS -> ConvertFrom-String 3.1.0.0 Microsoft.PowerShell.Utility ``` > to query specific key, just add the key to path `dir alias:\some_thing` > to query value only, add `$` to env `$alias:some_thing` --- #### Steps - in order to persist configuration across terminal session we'll have to create a profile for powershell by do the following command ```powershell new-item -path $profile -itemtype file -force ``` - now open the profile in your favourite ide and add the following script ```powershell function java8 { $Env:JAVA_HOME = "[your JDK ROOT PATH]" refreshenv } function java11 { $Env:JAVA_HOME = "[your JDK ROOT PATH]" refreshenv } ... ``` - re-open your powershell and see if the function getting load normally, however on the first time you might ran into this problem ```powershell . : File ...\WindowsPowerShell\Microsoft.PowerShell_profile.ps1 cannot be loaded because running scripts is disabled on this system. For more information, see about_Execution_Policies at https:/go.microsoft.com/fwlink/?LinkID=135170. At line:1 char:3 + . '...\WindowsPowerShell\Microsoft.Powe ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : SecurityError: (:) [], PSSecurityException + FullyQualifiedErrorId : UnauthorizedAccess ``` > this [stackoverflow](https://stackoverflow.com/a/26955050) answer give a great explanation on how to solve this issue without compromise much of your machine security - after powershell started successfully, now it's the time to test our little script ```powershell PS C:\Users\Rujra> java8 Refreshing environment variables from registry for cmd.exe. Please wait...Finished.. PS C:\Users\Rujra> $env:PATH %JAVA_HOME%\bin;[other PATH env blah blah blah] PS C:\Users\Rujra> $env:JAVA_HOME C:\Program Files\Eclipse Adoptium\jdk-8.0.345.1-hotspot PS C:\Users\Rujra> java -version openjdk version "17.0.4.1" 2022-08-12 OpenJDK Runtime Environment Temurin-17.0.4.1+1 (build 17.0.4.1+1) OpenJDK 64-Bit Server VM Temurin-17.0.4.1+1 (build 17.0.4.1+1, mixed mode, sharing) ``` > noticed that even with `refreshenv` it didn't worked, this is because it refresh `cmd.exe` and not `powershell.exe` we'll have to come up with another solution - from previous test, we'll see that it didn't worked as we expected, so, let's try another method by modify our script as below ```powershell function java8 { $Env:JAVA_HOME = "[your JDK ROOT PATH]" $env:Path = [System.Environment]::GetEnvironmentVariable("Path","Machine") } function java11 { $Env:JAVA_HOME = "[your JDK ROOT PATH]" $env:Path = [System.Environment]::GetEnvironmentVariable("Path","Machine") } ... ``` > this will replace `refreshenv` with manually load new env var from the machine env var to current `powershell` session - now let's close and re-open `powershell` and see if this time it working correctly. ```powershell PS C:\Users\Rujra> $env:PATH %JAVA_HOME%\bin;[other PATH env blah blah blah] PS C:\Users\Rujra> java -version openjdk version "17.0.4.1" 2022-08-12 OpenJDK Runtime Environment Temurin-17.0.4.1+1 (build 17.0.4.1+1) OpenJDK 64-Bit Server VM Temurin-17.0.4.1+1 (build 17.0.4.1+1, mixed mode, sharing) PS C:\Users\Rujra> $env:JAVA_HOME PS C:\Users\Rujra> java11 PS C:\Users\Rujra> $env:PATH C:\Program Files\Eclipse Adoptium\jdk-11.0.16.101-hotspot\bin;[other PATH env blah blah blah] PS C:\Users\Rujra> $env:JAVA_HOME C:\Program Files\Eclipse Adoptium\jdk-11.0.16.101-hotspot PS C:\Users\Rujra> java -version openjdk version "11.0.16.1" 2022-08-12 OpenJDK Runtime Environment Temurin-11.0.16.1+1 (build 11.0.16.1+1) OpenJDK 64-Bit Server VM Temurin-11.0.16.1+1 (build 11.0.16.1+1, mixed mode) ``` > now it's working, a bit easier to config than `CMD` for sure, cheers 🥂 --- ## 🖲️ Cmder Now we've come to the last terminal I'll config for this blog, The powerful [Cmder](https://cmder.app/) Cmder itself has many features off-the-shelf including linux commands that you can use alongside your normal windows commands whether it's `ls -lha` `dir` etc, but now I'll add a bit more power to it by adding ability to dynamically switch JDK version with alias. > ! important: before we proceed please make sure you have set the `PATH` variable with `%JAVA_HOME%\bin` at the top like we did in `CMD` or `Powershell` steps - first, after you've downloaded and extracted cmder to your machine, you'll have something like this below ```bash D:\Programs\Cmder λ ls -lha total 169K drwxr-xr-x 1 Rujra 197609 0 Feb 3 2022 ./ drwxr-xr-x 1 Rujra 197609 0 Sep 4 13:47 ../ drwxr-xr-x 1 Rujra 197609 0 Jan 26 2020 bin/ -rwxr-xr-x 1 Rujra 197609 139K Jan 17 2022 Cmder.exe* -rw-r--r-- 1 Rujra 197609 33 Mar 9 2020 cmder_shell.bat drwxr-xr-x 1 Rujra 197609 0 Sep 27 18:56 config/ drwxr-xr-x 1 Rujra 197609 0 Jan 26 2020 icons/ -rw-r--r-- 1 Rujra 197609 1.1K Jan 17 2022 LICENSE drwxr-xr-x 1 Rujra 197609 0 Oct 31 2021 opt/ drwxr-xr-x 1 Rujra 197609 0 Feb 3 2022 vendor/ -rw-r--r-- 1 Rujra 197609 0 Jan 17 2022 'Version 1.3.19.1181' ``` - inside `config` folder there will be some config files, but we will be focus on 2 configs only - user_aliases.cmd - user_profile.cmd ```bash D:\Programs\Cmder\config λ ls -lha total 508K drwxr-xr-x 1 Rujra 197609 0 Sep 27 18:58 ./ drwxr-xr-x 1 Rujra 197609 0 Feb 3 2022 ../ -rw-r--r-- 1 Rujra 197609 4.2K Sep 27 18:58 clink.log -rw-r--r-- 1 Rujra 197609 377K Sep 27 18:56 clink_history -rw-r--r-- 1 Rujra 197609 121 Sep 27 18:58 clink_history_23924 -rw-r--r-- 1 Rujra 197609 97 Sep 27 18:56 clink_history_23924.removals -rw-r--r-- 1 Rujra 197609 0 Sep 27 18:56 clink_history_23924~ -rw-r--r-- 1 Rujra 197609 507 Oct 31 2021 clink_settings -rw-r--r-- 1 Rujra 197609 2.0K Mar 16 2022 cmder_prompt_config.lua -rw-r--r-- 1 Rujra 197609 29K May 11 2021 mini_dump.dmp drwxr-xr-x 1 Rujra 197609 0 Feb 3 2022 profile.d/ -rw-r--r-- 1 Rujra 197609 887 Jan 17 2022 Readme.md -rw-r--r-- 1 Rujra 197609 672 Sep 26 19:29 user_aliases.cmd -rw-r--r-- 1 Rujra 197609 967 Sep 26 18:42 user_profile.cmd -rw-r--r-- 1 Rujra 197609 408 Dec 23 2018 user_profile.ps1 -rw-r--r-- 1 Rujra 197609 54K Jun 23 16:18 user-ConEmu.xml ``` - inside `user_profile.cmd` add the following config ```bat ... :: JAVA config set JAVA_8_HOME="[your JDK ROOT PATH]" set JAVA_11_HOME="[your JDK ROOT PATH]" :: Other jdk you're using ... ``` - now after we set env on the profile, we'll set alias in `user_aliases.cmd` to switch the java version whenever we needed. ```bat ;= JAVA_HOME java8=set JAVA_HOME=%JAVA_8_HOME%&refreshenv java11=set JAVA_HOME=%JAVA_11_HOME%&refreshenv ``` - saves and open up `Cmder` and let's try the new alias ```bash C:\Users\Rujra λ echo %PATH% %JAVA_HOME%\bin;[other PATH env blah blah blah]; C:\Users\Rujra λ echo %JAVA_HOME% %JAVA_HOME% C:\Users\Rujra λ java -version openjdk version "17.0.4.1" 2022-08-12 OpenJDK Runtime Environment Temurin-17.0.4.1+1 (build 17.0.4.1+1) OpenJDK 64-Bit Server VM Temurin-17.0.4.1+1 (build 17.0.4.1+1, mixed mode, sharing) C:\Users\Rujra λ java11 Refreshing environment variables from registry for cmd.exe. Please wait...Finished.. C:\Users\Rujra λ echo %PATH% "C:\Program Files\Eclipse Adoptium\jdk-11.0.16.101-hotspot"\bin;[other PATH env blah blah blah]; C:\Users\Rujra λ echo %JAVA_HOME% "C:\Program Files\Eclipse Adoptium\jdk-11.0.16.101-hotspot" C:\Users\Rujra λ java -version openjdk version "11.0.16.1" 2022-08-12 OpenJDK Runtime Environment Temurin-11.0.16.1+1 (build 11.0.16.1+1) OpenJDK 64-Bit Server VM Temurin-11.0.16.1+1 (build 11.0.16.1+1, mixed mode) ``` > work like a charm 😁👾 --- and that's it, thank you for reading, this is my first (finished)blog, any feedbacks & suggestions are gladly welcome! 🙌 ---

zeagur

Running multiple version of JDK in Windows commandLine, the fun? way

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