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Difference between revisions of "Variables (PowerShell)"
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{{Depreciated|category=Variables_(PowerShell)}} | |||
__TOC__ | __TOC__ | ||
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== Arrays == | == Arrays == | ||
<source lang="powershell"> | <source lang="powershell"> | ||
$array = @() | $array = @() # Create blank array | ||
$array += 34 | $array = @("one", "two", 3) # Create an array with some values | ||
$array += 34 # Add value to end of array | |||
</source> | </source> | ||
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To force the creation of a .NET array from a PowerShell CmdLet, create one in a fashion such as this... | To force the creation of a .NET array from a PowerShell CmdLet, create one in a fashion such as this... | ||
<source lang="powershell"> | <source lang="powershell"> | ||
$a = New-Object System.Collections.ArrayList(,(Get-Content test.txt)) | $a = New-Object System.Collections.ArrayList # Empty array | ||
$a = New-Object System.Collections.ArrayList(,(Get-Content test.txt)) # Populated with contents of test.txt | |||
</source> | </source> | ||
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</source> | </source> | ||
== Datetime == | == Object Types == | ||
=== Datetime === | |||
The object structure: http://msdn.microsoft.com/en-us/library/system.datetime.aspx | The object structure: http://msdn.microsoft.com/en-us/library/system.datetime.aspx | ||
=== Improper (US) Formatting === | ==== Improper (US) Formatting ==== | ||
Be aware that if you live somewhere dates are normally formatted properly (eg not the USA), then PowerShell (or probably the underlying DateTime object type as this sort of problem seems to rear its head at unexpected moments when working on Windows) has a nasty habit of returning a string formatted with day and month swapped around when coming from a script. | Be aware that if you live somewhere dates are normally formatted properly (eg not the USA), then PowerShell (or probably the underlying DateTime object type as this sort of problem seems to rear its head at unexpected moments when working on Windows) has a nasty habit of returning a string formatted with day and month swapped around when coming from a script. | ||
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If your dates are getting mixed up, it may not be your mistake, and it may be that you've fallen fowl of the problem as well. | If your dates are getting mixed up, it may not be your mistake, and it may be that you've fallen fowl of the problem as well. | ||
=== Formatting === | ==== Formatting ==== | ||
To control how a DateTime is displayed you can pass it through <code> Get-Date </code> with the '''<code> -uFormat </code>''' option... | To control how a DateTime is displayed you can pass it through <code> Get-Date </code> with the '''<code> -uFormat </code>''' option... | ||
<source lang="powershell">Get-Date $datetime -uFormat "%R hrs, %a %d %b %Y"</source> | <source lang="powershell">Get-Date $datetime -uFormat "%R hrs, %a %d %b %Y"</source> | ||
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For the full list of formatting options see http://technet.microsoft.com/en-us/library/ee692801.aspx, and even more detail at http://msdn.microsoft.com/en-us/library/system.globalization.datetimeformatinfo.aspx | For the full list of formatting options see http://technet.microsoft.com/en-us/library/ee692801.aspx, and even more detail at http://msdn.microsoft.com/en-us/library/system.globalization.datetimeformatinfo.aspx | ||
=== Converters === | ==== Converters ==== | ||
<source lang="powershell"> | <source lang="powershell"> | ||
function ConvertLocalToUnix([datetime]$datetime) | function ConvertLocalToUnix([datetime]$datetime) | ||
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{ | { | ||
[timezone]::CurrentTimeZone.ToLocalTime(([datetime]'1/1/1970').AddSeconds($sincepoch)) | [timezone]::CurrentTimeZone.ToLocalTime(([datetime]'1/1/1970').AddSeconds($sincepoch)) | ||
} | |||
</source> | |||
=== IP Address === | |||
The object structure: http://msdn.microsoft.com/en-us/library/system.net.ipaddress | |||
To create an IP address object... | |||
<source lang="powershell"> | |||
$ip = [System.Net.IPAddress]::Parse("192.168.1.123") | |||
</source> | |||
To confirm a supplied address is valid... | |||
<source lang="powershell"> | |||
if ( [System.Net.IPAddress]::TryParse($IP2test) ) { | |||
Write-Host "$IP2test is a valid address" | |||
} | } | ||
</source> | </source> | ||
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== Macros / Built-in Variables == | == Macros / Built-in Variables == | ||
{|class="vwikitable" | {|class="vwikitable" | ||
|- | |- | ||
! Variable !! Description | ! Variable !! Description | ||
|- | |- | ||
| <code> $_ </code> || | | <code> $_ </code> || Variable passed through pipeline from previous command | ||
|- | |- | ||
| <code> $? </code> || Success/failure of previous statement - see [[#Basic_Error_Handler|Basic_Error_Handler]] | | <code> $? </code> || Success/failure of previous statement - see [[#Basic_Error_Handler|Basic_Error_Handler]] | ||
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| <code> $foreach </code> || Enumerator in a foreach loop | | <code> $foreach </code> || Enumerator in a foreach loop | ||
|- | |- | ||
| <code> $Host </code> || Information about the machine being executed on | | <code> $Host </code> || Information about the machine being executed on (can also use <code>Get-Host</code> | ||
|- | |- | ||
| <code> $args </code> || Array of arguments passed to a script - see [[#Script_Arguments|Script_Arguments]] | | <code> $args </code> || Array of arguments passed to a script - see [[#Script_Arguments|Script_Arguments]] | ||
|} | |} | ||
=== $env === | |||
This object contains all local system environment variables. For example '''<code>$env:COMPUTERNAME</code>''' provides you with the local system's computer name. | |||
For a full list use... | |||
<source lang="powershell"> | |||
Get-ChildItem env: | |||
</source> | |||
...or for some commonly used ones... | |||
{|class="vwikitable" | |||
|- | |||
! Variable !! Description !! Example data | |||
|- | |||
| APPDATA || Application data path || C:\Users\RodHull\AppData\Roaming | |||
|- | |||
| COMPUTERNAME || Local System's hostname || LAPTOP-01 | |||
|- | |||
| LOGONSERVER || Domain Controller Logged into || DC-SERVER-03 | |||
|- | |||
| PROCESSOR_ARCHITECTURE || CPU Architecture || AMD64 | |||
|- | |||
| USERDOMAIN || Logged in user's domain || DOMAIN.COM | |||
|- | |||
| USERNAME || Local System's hostname || rodhull | |||
|} | |||
[[category:PowerShell]] | [[category:PowerShell]] | ||