Hi, I’m Tomoya.
It’s been a while since I posted last time.
This time I’ll be writing about Powershell because I’ve been working on writing scripts with Powershell recently. It will be just a personal memo tho.

About Powershell

• Shell script initially developed by Microsoft
• Successor from DOS and VBScript, and based on .NET framework,
• Works not only on Windows but also on Linux and MacOS

Installation

• If Windows, it’s already installed by default.
• If Mac, you can easily install Powershell here（it’s all Japanese tho）

In terms of text editor, Powershell ISE is one of the best choices in general. However, I’ll use Visual Studio code because I’m used to it and able to do similar things on VS code too, with Powershell extension which works like IDE for Powershell.

How to run Powershell scripts

File extension for Powershell is .ps1. Let’s just execute hello_world.ps1 which just outputs “Hello world!“.

# hello_world.ps1

write-host Hello world!

You created the file, and run it on terminal with just file name.

# terminal

hello_world.ps1 （you can omit ps1）

# output
Hello world!

How to write scripts

Powershell commands（commandlet）are basically consist of {Verb - Noun}.
And luckily Powershell commands have alias for Linux and MacOS commands as well so you can use something like ls on Powershell.

Basic commands

More commands for scripting

To write more practical scripts, you need to understand and make use of complicated commands.

Out-File

This command outputs a result of shell commands to another file.
(-encoding for charset, -append for appending to a remaining file)

"abcdefg" | Out-File sample.txt -encoding UTF8 -append

# If the path already defined, you can write a script like this too
$newFile = ‘c:\tmp\sample.txt’
"abcdefg" > $newFile

Split-Path

This command splits a remaining path and return a part of it. (-Parent for parent path -Leaf for a path at tip)

Split-Path -Parent C:\Folder1\Folder2\FileA.txt

# output
C:\Folder1\Folder2

Split-Path -Leaf C:\Folder1\Folder2\FileA.txt

# output
FileA.txt

[System.Windows.Forms.MessageBox]::show()

This shows a message window and return a value that users choose.

# You need to load Assembly
Add-Type -AssemblyName System.Windows.Forms

# Ask question here
$result = [System.Windows.Forms.MessageBox]::Show("実行しますか？","確認","YesNo","Question","Button2")

# Show the result
If($result -eq "Yes"){
  [void][System.Windows.Forms.MessageBox]::Show("Yesが押されました。","結果","OK","Information")
}Else{
  [void][System.Windows.Forms.MessageBox]::Show("Noが押されました。","結果","OK","Information")
}

Select-String

This command extracts a specific string based on regex(Regular Expression).

$sourceFile = ‘C:\tmp\source.txt’
$regex = ‘\b[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}\b’
select-string -Path $sourceFile -Pattern $regex -AllMatches -Encoding default

There’re more other commands which I would be using in near future so I’ll just add those commands here on this post…

Tomoya