Powershell Programming

I am just putting togetther simple things that I come to know about powershell and i just said wow!

1. How to Merge XML files using powershell:

Let consider we have two below xml files to merge:

C:/MainFile.xml
<?xml version="1.0"?>
<catalog>
   <Recipe id="rc501">
      <author>Suhas, Tiwaskar</author>
      <title>C++ Cofta</title>
      <price>98.95</price>
      <originated_from>Sewagram</originated_from>
   </Recipe>
   <Recipe id="rc502">
      <author>Harish, Datey</author>
      <title>Java Malai</title>
      <price>1765.00</price>
      <originated_from>Khandesh</originated_from>
   </Recipe>
</catalog>

C:/Delta.xml
<?xml version="1.0"?>
<catalog>
   <Recipe id="rc503">
      <author>Vaibhav, Wakodikar</author>
      <title>.Net Rajma</title>
      <price>98.95</price>
      <originated_from>Karve, Nagar</originated_from>
   </Recipe>
   <Recipe id="rc504">
      <author>Amit, Nandurikar</author>
      <title>PHP Rassam</title>
      <price>116.00</price>
      <originated_from>Aurangabad</originated_from>
   </Recipe>

</catalog>

Now create one more File with name mergeXml.ps1 in C:\  with below content:

[xml]$File1 = Get-Content C:\MainFile.xml
[xml]$File2 = Get-Content C:\Delta.xml
ForEach ($XmlNode in $File2.DocumentElement.ChildNodes){$File1.DocumentElement.AppendChild($File1.ImportNode($XmlNode, $true))}
$File1.Save('C:\Merged.xml')


now on powershell window run this script by running "powershell C:\mergeXML.ps1" it will merge two xml files.


you may get error "The input document has exceeded a limit set by MaxCharactersFromEntities". you need to make one trick so that validator will turn off. Upper code will changed to:

$MainFile = New-Object System.Xml.XmlDocument
$MainFile.XmlResolver = $null
$MainFile.Load($args[0])

$DeltaFile = New-Object System.Xml.XmlDocument
$DeltaFile.XmlResolver = $null
$DeltaFile.Load($args[1])


ForEach ($XmlNode in $DeltaFile.DocumentElement.ChildNodes){$MainFile.DocumentElement.AppendChild($MainFile.ImportNode($XmlNode, $true))}
$MainFile.Save($args[0])

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2. Get the output of command in variable using Powershell

$output = cmd /c "set JAVA_HOME"

this will push output of command "set JAVA_HOME" to $output variable, after which you can print that variable content using:

return $output

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3. Splitting the content using Powershell

$output = cmd /c "set"

this will just push output of command set to variable $output, if we want to split the content by new line character

ForEach($line in $output){     //looping on lines

    $split = $line -split "="  //split by "="

    $varName = $split[0]

    Write-Host $varName        //writing to console

}

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4. How to know if variable is empty or not

There are multiple ways but I am keeping here the simplest one:

if($yourName) {           

Write-Host $yourName" is awesome!"      

}

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5. Error: “execution of scripts is disabled on this system”

Yes you need to set execution policy to powershell command prompt like below:

powershell.exe -ExecutionPolicy Unrestricted C:\SampleScript.ps1

this will bypass the restrictions and execute the command.

Documentation

Documentation2

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6. Downloading the Amazon S3 Bucket content

# Your account access key - must have read access to your S3 Bucket

$accessKey = "your_access_key"

# Your account secret access key

$secretKey = "your_success_key"

# The region associated with your bucket e.g. eu-west-1, us-east-1, us-west-2, eu-west-1, eu-central-1, ap-southeast-1, ap-northeast-1, ap-southeast-2, ap-northeast-2, sa-east-1. Documentation 

$region = "us-east-1"

# The name of your S3 Bucket

$bucket = "your_s3bucket_name"

# The folder in your bucket to copy, including trailing slash. Leave blank to copy the entire bucket

$keyPrefix = "folder_name/"

# The local file path where files should be copied

$localPath = "D:\YourLocalFolder\"

$objects = Get-S3Object -BucketName $bucket -KeyPrefix $keyPrefix -AccessKey $accessKey -SecretKey $secretKey -Region $region

foreach($object in $objects) {

$localFileName = $object.Key -replace $keyPrefix, ''

if ($localFileName -ne '') {

$localFilePath = Join-Path $localPath $localFileName

Copy-S3Object -BucketName $bucket -Key $object.Key -LocalFile $localFilePath -AccessKey $accessKey -SecretKey $secretKey -Region $region

}

}

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7. Creating directory using powershell script

New-Item -ItemType directory -Path C:\Scripts\newDir

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8. Adding Content at the end of File

Add-Content C:\Windows\System32\drivers\etc\hosts "`n127.0.0.0 hostname"

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