R Geturl Error Catch Try Again

Introduction to Attempt-take hold of in PowerShell

A skillful practice while working on any script or program is to have a mechanism for error treatment. Though it may take a little bit of additional time, its rewards are priceless. Try-catch in PowerShell in this commodity, it is not possible for whatsoever script or plan to run without any error or outcome 100% of the time. It is not necessary that an error ever must occur because of logical errors in the script. Many external factors may also affect the successful running of the script. To avoid these kinds of surprises, it is better to implement the error treatment mechanism.

There are 2 types of errors that can be occurring during script execution. They are terminating and non-terminating errors. As the name implies, terminating error will finish the plan from further execution, whereas a non-terminating error will non stop the execution. An example of terminating error would exist a syntax error whereas an instance of non-terminating error would be missing a file.

Understanding Try-Catch

In PowerShell, the fault handling is done through trial and catch blocks. The endeavor block will have the code, that may probable throw an error. The catch block contains the code or action to be executed in case of an error that is thrown by the try cake. Additionally, a final cake can exist used to free upwardly the resource. Mostly, non-terminating errors tin't exist handled in PowerShell. To handle such errors, they needed to be specifically converted to as a terminating error. This can exist done using ErrorActionPreference.

Syntax:

The general syntax of the endeavour-catch cake is as follows

Attempt
{
//code1 that may generate exception
//code2 that may generate exception
//code3 that may generate exception
//to catch non-terminating error, convert them to terminating error
}
Catch(error)
{
//code to exist executed
//multiple take hold of blocks can be included, or the same catch cake tin can be used to catch multiple exceptions
// the error information is nowadays inside the $_ variable
//The error can be logged to a text file or can trigger an electronic mail to inform some user about the fault
}
Finally
{
//lawmaking to be executed
//this is an optional block of lawmaking
}


The syntax for Multiple Catch:

endeavour
{
//code to be executed
}
catch [System.IO.DirectoryNotFoundException] {
Write-Output "Directory Not Exception"
}
grab [Organisation.IO.IOException] {
Write-Output "Input/output Exception"
}
grab [System.IO.FileNotFoundException] {
Write-Output "File Not Found Exception"
}

Parameters

Setting the Error action parameter can be done in many ways. The following are the possible values for the ErrorAction parameter.

• If -ErrorAction Stop: Information technology throws the mistake and stops the execution of the plan.
• If -ErrorAction Enquire/Continue: Throws error but continues with the execution of the program.
• If -ErrorAction SilentlyContinue: Error is not thrown, and the execution continues
• If – ErrorAction Ignore: Fault is non thrown, and the execution continues

The deviation between silently continue and ignore is that silently stores the error details in the $error variable whereas ignore doesn't do that.

Examples of Try-catch in PowerShell

The below is a sample usage of Try, take hold of block:

Code:

try
{
dfdgfdfgf
sfsdf
dsfdfdsf
}
grab
{
write-host "Exception caught"
}

Output:

Example #ane

Various parameters of ErrorActionPreference.

Code:

Write-Host "Instance Error Action Preference: stop"
$ErrorActionPreference = 'Stop'
$test= 9/0
Write-Host "Nevertheless running"

Output:

As you can see, the execution is stopped immediately afterward an mistake has occurred.

Let'due south change it to continue

Code:

Write-Host " Demo"
$ErrorActionPreference = 'Continue'
$test= 9/0
Write-Host "Notwithstanding running"

Output:

If you lot run across in the in a higher place output, "Still running" is printed fifty-fifty after the occurrence of fault

Let's see the same input with ErrorActionSet set as 'Silently continue'

Code:

Write-Host " Sample test"
$ErrorActionPreference = 'SilentlyContinue'
$examination= nine/0
Write-Host "Nonetheless running"

Output:

As you can see, none of the errors are displayed on the screen and the execution is continued.

Example #2

Writing Error Message to Console.

Lawmaking:

Try {
Go-ThisWontWorktestcommand
}
Catch  {
Write-Host "The command ran is not found"`due north -ForegroundColor Blue
Write-Host "Message: [$($_.Exception.Bulletin)"] -ForegroundColor Red -BackgroundColor DarkBlue
}

Output:

Error Handling Best Practices

• If there is an exception that sits across your face, attempt to detect a solution to avert that completely instead of going for exception treatment.
• Cheque the functionality of the code in case if the aforementioned error occurs frequently.
• Endeavour to catch the specific type of exception that is trying block is going to render, in case of not knowing the blazon of exception that is going to occur create a generic catch block.
• Better to capture the exception message in an output file along with a timestamp and exception message.
• It is appropriate not to create an empty catch block.

Decision

Thus, the article covered in detail about the endeavor block feature in PowerShell. For any person aspiring to be a good developer in PowerShell, it is important that they accept a very potent understanding of the mistake handling mechanism. In the case of automated jobs, without mistake handling mechanisms implemented in the lawmaking, it will exist a nightmare for the administrator to understand what the issue is or when an outcome has occurred.

Recommended Articles

This is a guide to Try-catch in PowerShell. Hither we discuss the Understanding of Endeavour-Catch, Mistake treatment best practices forth with the examples. You may also await at the post-obit articles to larn more –

1. Loops in PowerShell
2. PowerShell Environs Variables
3. How to Format the Tabular array in Powershell?
4. Guide to vii Different PowerShell Tools

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Source: https://www.educba.com/try-catch-in-powershell/

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