PowerShell Cheatsheet
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PowerShell is a windows command-line shell designed especially for system administrators. It was built on top of the .NET Framework common language runtime (CLR) and the .NET Framework. So, it accepts and returns .NET Framework objects.
PowerShell works in both INTERACTIVE mode and SCRIPT mode. It possesses cmdlet (pronounced "command-let") for doing pre-defined tasks.
There wont be much gain, without any pain. I would recommend learning powershell because of the advantages that it offers.
Advantages:
- Ease in accessing file systems
- Ability to access other data stores, such as registry and digital signature certificate stores.
- Open-source and increasing community base
- Apart from windows, it is extending support for Linux from next release.
- As PowerShell is tightly coupled with .NET framework. So, .NET objects can be used.
- Ease in working with all Microsoft products (Office suite, Client OS, Server OS, IIS, Databases, Visual Studio Suite, etc.)
- Ability to connect to existing windows administrative functionality:
- WMI
- Microsoft .NET framework
- COM (Component Object Model)
- ADSI (Active Directory Services Interface)
- Can be used to automate almost any administrative task
Initially, when windows was launched for the first time, it came with the MS-DOS. Later, in 1981, batch script (CMD) was introduced, followed by VBScript in 1996 and PowerShell in 2006. PowerShell script have .ps1 as the file extension. Here, the '1' in '.ps1' doesn't refer to the powerShell version; rather refers to the version of the engine, which runs the powerShell.
PowerShell 1.0
- Installed but not enabled on windows Vista and Server 2008
PowerShell 2.0
- Installed by default on Windows 7 and Server 2008 R2
- The PowerShell ISE is installed by default on Windows 7
- Can be installed on Windows XP and Server 2003 or Higher
PowerShell 3.0
- Installed by default on Windows 8 and Server 2012
- ISE is installed by default on Windows 8 and Server 2012 GUI
- Can be installed on Windows 7 and Server 2008 or Higher
- PowerShell Remoting is enabled by default on Server 2012
There exists some differences between these versions, and the latest version of PowerShell is 6.0. The suitable PowerShell version for windows servers is:
| PowerShell Version | Release Date | Default Windows Versions | Available Windows Versions |
|---|---|---|---|
| PowerShell 1.0 | November 2006 | Windows Server 2008 (*) | Windows XP SP2 |
| Windows XP SP3 | |||
| Windows Server 2003 SP1 | |||
| Windows Server 2003 SP2 | |||
| Windows Server 2003 R2 | |||
| Windows Vista | |||
| Windows Vista SP2 | |||
| PowerShell 2.0 | October 2009 | Windows 7 | |
| Windows Server 2008 R2 (**) Windows XP SP3 | |||
| Windows Server 2003 SP2 | |||
| Windows Vista SP1 | |||
| Windows Vista SP2 | |||
| Windows Server 2008 SP1 | |||
| Windows Server 2008 SP2 | |||
| PowerShell 3.0 | September 2012 | Windows 8 | |
| Windows Server 2012 Windows 7 SP1 | |||
| Windows Server 2008 SP2 | |||
| Windows Server 2008 R2 SP1 | |||
| PowerShell 4.0 | October 2013 | Windows 8.1 | |
| Windows Server 2012 R2 Windows 7 SP1 | |||
| Windows Server 2008 R2 SP1 | |||
| Windows Server 2012 | |||
| PowerShell 5.0 | February 2016 | Windows 10 | Windows 8.1 |
| Windows Server 2012 R2 |
Go to windows menu, and type Windows PowerShell (don't choose Windows PowerShell ISE) and open it.
To get the PowerShell version installed on the machine, type
PS C:\> $PSVersionTable
Name Value
---- -----
PSVersion 5.0.10586.672
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0...}
BuildVersion 10.0.10586.672
CLRVersion 4.0.30319.42000
WSManStackVersion 3.0
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1Observe that the PSVersion which is 5.0 in this case.
To get the Host details,
PS C:\> Get-Host
Name : ConsoleHost
Version : 5.0.10586.672
InstanceId : 7756acf5-225d-40b7-ac79-173bf20eadda
UI : System.Management.Automation.Internal.Host.InternalHostUserInterface
CurrentCulture : en-US
CurrentUICulture : en-US
PrivateData : Microsoft.PowerShell.ConsoleHost+ConsoleColorProxy
DebuggerEnabled : True
IsRunspacePushed : False
Runspace : System.Management.Automation.Runspaces.LocalRunspace
$env is a predefined variable in powershell. It will store the complete windows environment information.
Printing it barely doesn't result in any information.
PS C:\> $env
PS C:\>
The $env variable must be accompanied by the other corresponding variable.
PS C:\> $env:COMPUTERNAME
UDHAYPC
PS C:\> $env:USERNAME
UDHAY
PS C:\> $env:USERDNSDOMAIN
prakash.COM
PS C:\> $env:USERPROFILE
C:\Users\UDHAY
PS C:\> $env:ALLUSERSPROFILE
C:\ProgramData
PS C:\> $env:ComSpec
C:\Windows\system32\cmd.exe
PS C:\> $env:HOMEPATH
\Users\UDHAY
PS C:\> $env:HOMEDRIVE
C:
PS C:\> $env:ProgramFiles
C:\Program Files
NOTE: If you dont know all the variables part of it, after : type tab key to all those variables one-by-one.
PowerShell used a concept called Aliases to support commonly used commands in other Microsoft languages like Batch Script (CMD), VBScript, etc.
Commonly used Batch Script (CMD) commands such as dir, ls, cls, .... are supported in PowerShell.
PS C:\> Clear-Host # same as cls in CMD; clears the screenBut, they doesn't support those commands extensively. For example, dir will work; but not dir /A:D.
To explicitly run the commands and/or scripts of other language in powershell,
$command = @'
cmd.exe /C dir /A:D
'@
Invoke-Expression -Command:$command
But, let's ignore this until we understood this language syntax and semantics.
PowerShell possesses light-weight commands, called cmdlets, to do some specific tasks.
They use a consistent verb-noun structure, where the verb represents the action and the noun represents the object to operate on.
PowerShell cmdlets follow consistent naming patterns, ensuring that construction of a command is easy if you know the object that you want to work with.
All command categories take parameters and arguments. A parameter starts with a hyphen and is used to control the behavior of the command. An argument is a data value consumed by the command.
A simple PowerShell command has the following syntax:
command -parameter1 -parameter2 argument1, argument2
To get the list of approved verbs,
PS C:\> Get-Verb
Verb Group
---- -----
Add Common
Clear Common
Close Common
Copy Common
Enter Common
Exit Common
Find Common
Format Common
Get Common
Hide Common
Join Common
Lock Common
Move Common
New Common
Open Common
....
[Tailored the list]
The Grouping is done based on their common use.
Each Windows PowerShell verb is assigned to one of the following groups.
Common: Define generic actions that can apply to almost any cmdlet, such as Add.Communications: Define actions that apply to communications, such as Connect.Data: Define actions that apply to data handling, such as Backup.Diagnostic: Define actions that apply to diagnostics, such as Debug.Lifecycle: Define actions that apply to the lifecycle of a cmdlet, such as Complete.Security: Define actions that apply to security, such as Revoke.Other: Define other types of actions.
To get the list of all nouns,
PS C:\> Get-Command –Noun *
CommandType Name ModuleName
----------- ---- ----------
Function Clear-Host
Function Disable-PSTrace PSDiagnostics
Function Disable-PSWSManCombinedTrace PSDiagnostics
Function Disable-WSManTrace PSDiagnostics
Function Enable-PSTrace PSDiagnostics
Function Enable-PSWSManCombinedTrace PSDiagnostics
Function Enable-WSManTrace PSDiagnostics
Function Get-DscConfiguration PSDesiredStateConfiguration
Function Get-DscLocalConfigurationManager PSDesiredStateConfiguration
Function Get-DscResource PSDesiredStateConfiguration
Function Get-FileHash Microsoft.PowerShell.Utility
Function Get-IseSnippet ISE
Function Get-LogProperties PSDiagnostics
Function Get-Verb
...
[Tailored the list]
Observe that Get-Verb too is a noun.
Also, there is another command named Get-Command to get a particular set of commands.
To get all the command in the current user scope in a particular windows machine,
PS C:\> Get-Command -All
CommandType Name ModuleName
----------- ---- ----------
Alias cat -> Get-Content
Alias cd -> Set-Location
Alias chdir -> Set-Location
Alias clc -> Clear-Content
Alias clear -> Clear-Host
Alias clhy -> Clear-History
Alias history -> Get-History
Alias icim -> CimCmdlets
Function Get-IseSnippet ISE
Function Get-LogProperties PSDiagnostics
Function Get-User Carbon
Function Get-Verb
Function Invoke-AsWorkflow PSWorkflowUtility
Function New-IseSnippet ISE
Filter more
Cmdlet Set-ADAccountControl ActiveDirectory
Cmdlet Set-Alias Microsoft.PowerShell.Utility
Cmdlet Set-AppLockerPolicy AppLocker
Cmdlet Set-CimInstance CimCmdlets
Cmdlet Set-ExecutionPolicy Microsoft.PowerShell.Security
Cmdlet Set-JobTrigger PSScheduledJob
Cmdlet Set-MsolAdministrativeUnit MSonline
Cmdlet Set-MsolAdministrativeUnit MSOnlineExtended
Cmdlet Start-BitsTransfer BitsTransfer
Cmdlet Start-DscConfiguration PSDesiredStateConfiguration
Cmdlet Test-PSSessionConfigurationFile Microsoft.PowerShell.Core
Cmdlet Test-WSMan Microsoft.WSMan.Management
Cmdlet Unlock-ADAccount ActiveDirectory
Cmdlet Write-EventLog Microsoft.Powershell.Management
Cmdlet Write-Host Microsoft.PowerShell.Utility
...
[Tailored the list]
Also, the commands can be retrieved in terms of Name, Verb, Noun, Module,...
PowerShell also possesses a strong and unique feature called piping, which we can discuss under the piping section.
Once the command to work is known using Get-Command, the usage and syntax of that particular cmdlet can be learned using Get-Help.
To get the help for a particular cmdlet, say clear-Host,
PS C:\> Get-Help -Name clear-Host
NAME
Clear-Host
SYNOPSIS
Clears the display in the host program.
SYNTAX
Clear-Host [<CommonParameters>]
DESCRIPTION
The Clear-Host function removes all text from the current display, including commands and output that might have accumulated. When complete, it
displays the command prompt. You can use the function name or its alias, CLS.
Clear-Host affects only the current display. It does not delete saved results or remove any items from the session. Session-specific items, such
as variables and functions, are not affected by this function.
Because the behavior of the Clear-Host function is determined by the host program, Clear-Host might work differently in different host programs.
RELATED LINKS
Online version: http://technet.microsoft.com/library/hh852689(v=wps.630).aspx
Get-Host
Out-Host
Read-Host. Write-Host
REMARKS
To see the examples, type: "get-help Clear-Host -examples".
For more information, type: "get-help Clear-Host -detailed".
For technical information, type: "get-help Clear-Host -full".
For online help, type: "get-help Clear-Host -online"
Observe the 6 fields (Name, Synopsis, syntax, Description, Related Links, Remarks). These are common for all the results of get-Help
If usage by example is needed,
PS C:\> Get-Help -Name clear-Host -Examples
NAME
Clear-Host
SYNOPSIS
Clears the display in the host program.
-------------------------- EXAMPLE 1 --------------------------
C:\PS>cls
# Before
PS C:\>Get-Process
Handles NPM(K) PM(K) WS(K) VM(M) CPU(s) Id ProcessName
------- ------ ----- ----- ----- ------ -- -----------
843 33 14428 22556 99 17.41 1688 CcmExec
44 6 2196 4964 52 0.23 692 conhost
646 12 2332 4896 49 1.12 388 csrss
189 11 2860 7084 114 0.66 2896 csrss
78 11 1876 4008 42 0.22 4000 csrss
76 7 1848 5064 54 0.08 1028 dwm
610 41 23952 44048 208 4.40 2080 explorer
0 0 0 24 0 0 Idle
182 32 7692 15980 91 0.23 3056 LogonUI
186 25 7832 16068 91 0.27 3996 LogonUI
1272 32 11512 20432 58 25.07 548 lsass
267 10 3536 6736 34 0.80 556 lsm
137 17 3520 7472 61 0.05 1220 msdtc
447 31 70316 84476 201 1,429.67 836 MsMpEng
265 18 7136 15628 134 2.20 3544 msseces
248 16 6476 4076 76 0.22 1592 NisSrv
368 25 61312 65508 614 1.78 848 powershell
101 8 2304 6624 70 0.64 3648 rdpclip
258 15 6804 12156 50 2.65 536 services
...
PS C:\> cls
#After
PS C:>
Description
-----------
This command uses the CLS alias of Clear-Host to clear the current display.
To update the help (ensure proper internet connect, as it downloads from PowerShell site),
PS C:\> Update-Help
PS C:\>
By default, the Execution Policy is set to 'Restricted'. It is recommended to change it to Resmote Signed.
| Execution Policy | It's importance |
|---|---|
| Restricted | You can run commands, but you can't run scripts |
| All Signed | You can run commands, but you can only run digitally signed scripts |
| Remote Signed | You can run commands, local scripts and only scripts downloaded from the internet if they are digitally signed |
| Unrestricted | You can run commands and scripts with or without digital signatures |
| Bypass | Nothing is blocked and there are no warnings or prompts |
In windows menu, type Windows PowerShell, right-click on it and click Run as Administrator. Then type the below command to the ExecutionPolicy on that machine for that user.
PS C:\> Get-ExecutionPolicy
Restricted
By default, it will give the execution policy associated with the user who executed this command.
PS C:\> Get-ExecutionPolicy -Scope CurrentUser
Restricted
Also, replace the CurrentUser in the above command with a specific username on that machine, to know the execution policy associated with that user.
To Change the execution policy, to say unrestricted,
PS C:\> Set-ExecutionPolicy -ExecutionPolicy "unrestricted" -Scope CurrentUser
Execution Policy Change
The execution policy helps protect you from scripts that you do not trust. Changing the execution policy might expose
you to the security risks described in the about_Execution_Policies help topic at
http://go.microsoft.com/fwlink/?LinkID=135170. Do you want to change the execution policy?
[Y] Yes [N] No [S] Suspend [?] Help (default is "Y"): Y
PS C:\>
As it is customary to start with 'Hello world' when learning any language, Lets start with it.
PS C:\> Write-Host "Hello World!"
Hello World!
PS C:\> Write-Host 'Hello World!'
Hello World!
PS C:\> 'Hello World!'
Hello World!Observe that the string 'Hello World!' is printed on the console in three ways. But, single (') and double(") quotes won't work exactly same in all cases. we can discuss about it in later section.
Single-line comment
PS C:\> # Comments begin with a # (aka hashtag or pound sign)
PS C:\>Multi-line comment
PS C:\> <#
>> Comment blocks use angle brackets with comment sign
>> They can be multiline
>> #>
PS C:\>
Regions are not logical, but representational blocks of code.
NOTE: Regions have their importance in powershell ISE only. They are used to divide the script into logical code blocks.
PS C:\> #region
PS C:\> # Put your code here
PS C:\> #endregion
PS C:\>
These regions can also be named.
PS C:\> #region The Region Title is Optional
PS C:\>
PS C:\> # some code here
PS C:\>
PS C:\> #endregion The Region Title is Optional
PS C:\>
Special Characters in PowerShell
| Special Character | Meaning |
|---|---|
| " | The beginning( or end) of quoted text. Used to represent strings |
| ' | The beginning( or end) of quoted text. Used to represent strings. special characters lose their significance within single quotes |
| # | The beginning of a comment |
| $ | The beginning of a variable |
| & | Reserved for future use |
| () | Parentheses used for subexpressions |
| {} | Script block |
| ; | Statement Separator |
| | | Pipeline seperator |
| ` | Escape Character |
| ? | Alias operator for Where-Object |
| % | Alias Operator for for-loop |
All variables start with a $.
PS C:\> $hi = "Hello World"
Printing the value in variable
PS C:\> $hi
Hello World
This is a shortcut to Write-Host
PS C:\> Write-Host $hi
Hello World
Variables are objects, and to get their data type,
PS C:\> $hi.GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True String System.Object
GetType() is one method, applicable on '$hi' object
To display all the members of this variable (object)
PS C:\> $hi | Get-Member
TypeName: System.String
Name MemberType Definition
---- ---------- ----------
Clone Method System.Object Clone(), System.Object ICloneable.Clone()
CompareTo Method int CompareTo(System.Object value), int CompareTo(string strB), int IComparab...
Contains Method bool Contains(string value)
CopyTo Method void CopyTo(int sourceIndex, char[] destination, int destinationIndex, int co...
EndsWith Method bool EndsWith(string value), bool EndsWith(string value, System.StringCompari...
Equals Method bool Equals(System.Object obj), bool Equals(string value), bool Equals(string...
GetEnumerator Method System.CharEnumerator GetEnumerator(), System.Collections.IEnumerator IEnumer...
GetHashCode Method int GetHashCode()
GetType Method type GetType()
GetTypeCode Method System.TypeCode GetTypeCode(), System.TypeCode IConvertible.GetTypeCode()
IndexOf Method int IndexOf(char value), int IndexOf(char value, int startIndex), int IndexOf...
IndexOfAny Method int IndexOfAny(char[] anyOf), int IndexOfAny(char[] anyOf, int startIndex), i...
Insert Method string Insert(int startIndex, string value)
IsNormalized Method bool IsNormalized(), bool IsNormalized(System.Text.NormalizationForm normaliz...
LastIndexOf Method int LastIndexOf(char value), int LastIndexOf(char value, int startIndex), int...
LastIndexOfAny Method int LastIndexOfAny(char[] anyOf), int LastIndexOfAny(char[] anyOf, int startI...
Normalize Method string Normalize(), string Normalize(System.Text.NormalizationForm normalizat...
PadLeft Method string PadLeft(int totalWidth), string PadLeft(int totalWidth, char paddingChar)
PadRight Method string PadRight(int totalWidth), string PadRight(int totalWidth, char padding...
Remove Method string Remove(int startIndex, int count), string Remove(int startIndex)
Replace Method string Replace(char oldChar, char newChar), string Replace(string oldValue, s...
Split Method string[] Split(Params char[] separator), string[] Split(char[] separator, int...
StartsWith Method bool StartsWith(string value), bool StartsWith(string value, System.StringCom...
Substring Method string Substring(int startIndex), string Substring(int startIndex, int length)
ToBoolean Method bool IConvertible.ToBoolean(System.IFormatProvider provider)
ToByte Method byte IConvertible.ToByte(System.IFormatProvider provider)
ToChar Method char IConvertible.ToChar(System.IFormatProvider provider)
ToCharArray Method char[] ToCharArray(), char[] ToCharArray(int startIndex, int length)
ToDateTime Method datetime IConvertible.ToDateTime(System.IFormatProvider provider)
ToDecimal Method decimal IConvertible.ToDecimal(System.IFormatProvider provider)
ToDouble Method double IConvertible.ToDouble(System.IFormatProvider provider)
ToInt16 Method int16 IConvertible.ToInt16(System.IFormatProvider provider)
ToInt32 Method int IConvertible.ToInt32(System.IFormatProvider provider)
ToInt64 Method long IConvertible.ToInt64(System.IFormatProvider provider)
ToLower Method string ToLower(), string ToLower(cultureinfo culture)
ToLowerInvariant Method string ToLowerInvariant()
ToSByte Method sbyte IConvertible.ToSByte(System.IFormatProvider provider)
ToSingle Method float IConvertible.ToSingle(System.IFormatProvider provider)
ToString Method string ToString(), string ToString(System.IFormatProvider provider), string I...
ToType Method System.Object IConvertible.ToType(type conversionType, System.IFormatProvider...
ToUInt16 Method uint16 IConvertible.ToUInt16(System.IFormatProvider provider)
ToUInt32 Method uint32 IConvertible.ToUInt32(System.IFormatProvider provider)
ToUInt64 Method uint64 IConvertible.ToUInt64(System.IFormatProvider provider)
ToUpper Method string ToUpper(), string ToUpper(cultureinfo culture)
ToUpperInvariant Method string ToUpperInvariant()
Trim Method string Trim(Params char[] trimChars), string Trim()
TrimEnd Method string TrimEnd(Params char[] trimChars)
TrimStart Method string TrimStart(Params char[] trimChars)
Chars ParameterizedProperty char Chars(int index) {get;}
Length Property int Length {get;}
Using some of those members
PS C:\> $hi.ToLower()
hello world
PS C:\> $hi.ToUpper()
HELLO WORLD
PS C:\> $hi.Length # No () as it is Property; not method
11
PS C:\> $hi.Replace("World", "PowerShell")
Hello PowerShell
Types are mutable. Their data types can also be changed
PS C:\> $hi = 5
PS C:\> $hi.GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Int32 System.ValueType
PS C:\> $hi | Get-Member
TypeName: System.Int32
Name MemberType Definition
---- ---------- ----------
CompareTo Method int CompareTo(System.Object value), int CompareTo(int value), int IComparable.CompareTo(System.Obj...
Equals Method bool Equals(System.Object obj), bool Equals(int obj), bool IEquatable[int].Equals(int other)
GetHashCode Method int GetHashCode()
GetType Method type GetType()
GetTypeCode Method System.TypeCode GetTypeCode(), System.TypeCode IConvertible.GetTypeCode()
ToBoolean Method bool IConvertible.ToBoolean(System.IFormatProvider provider)
ToByte Method byte IConvertible.ToByte(System.IFormatProvider provider)
ToChar Method char IConvertible.ToChar(System.IFormatProvider provider)
ToDateTime Method datetime IConvertible.ToDateTime(System.IFormatProvider provider)
ToDecimal Method decimal IConvertible.ToDecimal(System.IFormatProvider provider)
ToDouble Method double IConvertible.ToDouble(System.IFormatProvider provider)
ToInt16 Method int16 IConvertible.ToInt16(System.IFormatProvider provider)
ToInt32 Method int IConvertible.ToInt32(System.IFormatProvider provider)
ToInt64 Method long IConvertible.ToInt64(System.IFormatProvider provider)
ToSByte Method sbyte IConvertible.ToSByte(System.IFormatProvider provider)
ToSingle Method float IConvertible.ToSingle(System.IFormatProvider provider)
ToString Method string ToString(), string ToString(string format), string ToString(System.IFormatProvider provider...
ToType Method System.Object IConvertible.ToType(type conversionType, System.IFormatProvider provider)
ToUInt16 Method uint16 IConvertible.ToUInt16(System.IFormatProvider provider)
ToUInt32 Method uint32 IConvertible.ToUInt32(System.IFormatProvider provider)
ToUInt64 Method uint64 IConvertible.ToUInt64(System.IFormatProvider provider)
Variables can also be strongly-typed.
PS C:\> [System.Int32]$myint = 42
PS C:\> $myint
42
PS C:\> $myint.GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Int32 System.ValueType
PS C:\> $myint = "This won't work"
Cannot convert value "This won't work" to type "System.Int32". Error: "Input string was not in a correct format."
At line:1 char:1
+ $myint = "This won't work"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : MetadataError: (:) [], ArgumentTransformationMetadataException
+ FullyQualifiedErrorId : RuntimeException
There are shortcuts for most .NET data types.
PS C:\> [int] $myotherint = 42
PS C:\> $myotherint.GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Int32 System.ValueType
PS C:\> [string] $mystring="PowerShell"
PS C:\> $mystring.GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True String System.Object
Others include short, float, decimal, single, bool, byte, etc.
Not just variables have types - so do static values.
PS C:\> "PowerShell Rocks".GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True String System.Object
Accessing methods on objects
PS C:\> "PowerShell Rocks".ToUpper()
POWERSHELL ROCKS
PS C:\> "PowerShell Rocks".Contains("PowerShell")
True
For non-strings you need to wrap in () so PS will evaluate as an object.
PS C:\> (33).GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Int32 System.ValueType
| Operator | Importance |
|---|---|
| -eq | Equal to |
| -ne | Not equal to |
| -lt | Less Than |
| -gt | Greater then |
| -le | Less than or equal to |
| -ge | Greater then or equal to |
| | -in | See if value in an array| | -Like | Like wildcard pattern matching| | -NotLike | Not Like | | -Match | Matches based on regular expressions| | -NotMatch | Non-Matches based on regular expressions|
PS C:\> $var = 33
PS C:\> $var -gt 30
True
PS C:\> $var -lt 30
False
PS C:\> $var -eq 33
True
Calculations are like any other language.
PS C:\> $var = 3 * 11 # Also uses +, -, and /
PS C:\> $var
33
Supports post unary operators ++ and --
PS C:\> $var++
PS C:\> $var
34
And pre unary operators as well
PS C:\> ++$var
PS C:\> $var
35
PS C:\> $var = 33
PS C:\> $post = $var++
PS C:\> write-Host $post, $var
33 34
PS C:\>
PS C:\> $var = 33
PS C:\> $pre = ++$var
PS C:\> write-Host $pre, $var
34 34
Be cautious of Implicit Type Conversions
PS C:\> "42" -eq 42
True
PS C:\> 42 -eq "42"
True
Whatever is on the right is converted to the data type on the left can lead to some odd conversions.
PS C:\> 42 -eq "042" # True because the string on the right is coverted to an int
True
PS C:\> "042" -eq 42 # False because int on the right is converted to a string
False
PS C:\> # Booleans ( False and true)
PS C:\> $false
False
PS C:\> $true
True
PS C:\> $NULL # null type
PS C:\> Write-Host $NuLLObserve that nothing is display; even methods like GetType() doesn't work on this object.
To get the current working directory,
PS C:\> $pwd
Path
----
C:\
To get the Users Home Directory,
PS C:\> $Home
C:\Users\praud01
Information about a users scripting environment
PS C:\> $host # It is alias for Get-Host
Name : Windows PowerShell ISE Host
Version : 5.0.10586.672
InstanceId : 4e61fcaa-4155-4b95-aaa9-1b9c3186ed82
UI : System.Management.Automation.Internal.Host.InternalHostUserInterface
CurrentCulture : en-US
CurrentUICulture : en-US
PrivateData : Microsoft.PowerShell.Host.ISE.ISEOptions
DebuggerEnabled : True
IsRunspacePushed : False
Runspace : System.Management.Automation.Runspaces.LocalRunspace
PS C:\>
PS C:\> $PID # It results the process ID
12844
Info about the current version of Powershell
PS C:\> $PSVersionTable
Name Value
---- -----
PSVersion 5.0.10586.672
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0...}
BuildVersion 10.0.10586.672
CLRVersion 4.0.30319.42000
WSManStackVersion 3.0
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
PS C:\> $_ # Current Object; Used in loops to get the iterating object.
PS C:\> # Useful, mainly, in loops and exceptions
PS C:\> Set-Location "C:\Python27\Scripts"
PS C:\Python27\Scripts> # set-Location works in the same way as chdir
PS C:\Python27\Scripts> Get-ChildItem | Where-Object {$_.Name -like "*.cmd"}
Directory: C:\Python27\Scripts
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a---- 08-Mar-17 4:00 AM 1432 aws.cmd
-a---- 08-Mar-17 4:05 AM 24 hjson.cmd
-a---- 24-Jan-17 5:59 PM 151 wmitest.cmd
PS C:\Python27\Scripts> set-location c:\
PS C:\>
PS C:\> # Normal variable usage
PS C:\> $normal = 33
PS C:\> $normal
33
PS C:\> $text = "In The Morning"
PS C:\> $text
In The Morning
PS C:\> # Long version of $var1 = 33
PS C:\> New-Variable -Name var1 -Value 33
PS C:\> $var1
33NOTE: If you try to use New-Variable and it already exists, you get an error.
Try again with $var1 already existing.
PS C:\> New-Variable -Name var1 -Value 99
New-Variable : A variable with name 'var1' already exists.
At line:1 char:1
+ New-Variable -Name var1 -Value 99
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : ResourceExists: (var1:String) [New-Variable], SessionStateException
+ FullyQualifiedErrorId : VariableAlreadyExists,Microsoft.PowerShell.Commands.NewVariableCommand
PS C:\> $var1
33
PS C:\> # Displays the variable and it's value
PS C:\> Get-Variable var -valueonly
34
PS C:\> Get-Variable var
Name Value
---- -----
var 34
PS C:\> Get-Variable # Without params it shows all variables
Name Value
---- -----
$ var
? True
^ Get-Variable
APM_DATAPOINT_SOURCE public class APM_DATAPOINT_CLASS {...
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ATC_BASIC_ATTRIB_LIST {name, applicationName, backendName, components...}
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AWS_GLOBAL_VAR_FILE \AWSGlobalVariables.ps1
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CLWORKSTATION_JAR_PATH \CLWorkstation.jar
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ConsoleFileName
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Playlisturl https://www.youtube.com/watch?v=yKstEJKdc4o
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PSCommandPath
PSCulture en-US
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PSHOME C:\Windows\System32\WindowsPowerShell\v1.0
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PSSessionApplicationName wsman
PSSessionConfigurationName http://schemas.microsoft.com/powershell/Microsoft.PowerShell
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PSVersionTable {PSVersion, PSCompatibleVersions, BuildVersion, CLRVersion...}
PWD C:\
ShellId Microsoft.PowerShell
StackTrace at CallSite.Target(Closure , CallSite , Object )...
talkIt System.__ComObject
text In The Morning
true True
var 34
var1 33
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XML_CONFIG_OBJECT CONFIG_CLASS
Assigning a new value to an existing variable
Method 1:
PS C:\> $var1 = "In The Morning"
Method 2:
PS C:\> Set-Variable -Name var1 -Value "In The Morning"
PS C:\> $var1
In The Morning
PS C:\> Set-Variable -Name var99 -Value "In The Morning"
Observe that set-variable works on objects that aren't created yet.
To clear the contents of a variable,
PS C:\> Clear-Variable -Name var1 # Same as $var1 = $null
PS C:\> $var1
PS C:\>
To set the variable to null object,
PS C:\> $var1 -eq $null
True
Even though the object contains null, it still exists.
PS C:\> Get-Variable var1
Name Value
---- -----
var1
String Quoting
PS C:\> "This is a string"
This is a string
PS C:\> 'This is a string too!'
This is a string too!Mixed quoted
PS C:\> 'I just wanted to say "Hello World", OK?'
I just wanted to say "Hello World", OK?
PS C:\> "I can't believe how cool Powershell is!"
I can't believe how cool Powershell is!
You can also double quote to get quotes in strings
PS C:\> "I just wanted to say ""Hello World"", OK?"
I just wanted to say "Hello World", OK?
PS C:\> 'I can''t believe how cool Powershell is!'
I can't believe how cool Powershell is!
Escape Sequences - use the backtick `
backspace `b (does not work in ISE, only the regular script window)
PS C:\> "Power`bShell"
PoweShell
newline `n
PS C:\> "Power`nShell"
Power
Shell
carriage return `r (doesn't really show anything)
PS C:\> "Power`rShell"
Shell
crlf rn
PS C:\> "Power`r`nShell"
Power
Shell
tabs
PS C:\> "Power`tShell"
Power Shell
.Replace is case-sensitive
PS C:\> 'Hello wOrld'.Replace('o', '1')
Hell1 wOrld
-Replace is case-insentive
PS C:\> 'Hello wOrld' -Replace 'o', '1'
Hell1 w1rld
But, we need to be careful when working with special characters.
PS C:\> 'Hello wOrld.'.Replace('.', '1') # Replaces only the dot(.) character
Hello wOrld1
PS C:\> 'Hello wOrld.' -Replace '.', '1' # Replaced the complete string. Assumes '.' as regex character
111111111111
PS C:\>
PS C:\> 'Hello wOrld.' -Replace [Regex]::Escape('.'), '1' # To escape a regex character
Hello wOrld1
PS C:\> 'Hello wOrld.' -Replace '\.', '1' # Regex characters can also be escaped with '\'
Hello wOrld1
PS C:\> 'Hello wOrld\' -Replace '\\', '1' # '\' character will be escaped with another '\'
Hello wOrld1
Here Strings are used when working with large blocks of text.
PS C:\> $heretext = @"
>> Some text here
>> Some more here
>> a bit more
>>
>> a blank line above
>> "@
PS C:\> $heretext
Some text here
Some more here
a bit more
a blank line above
The @ and quote must be last on starting line then first on ending line, also works with single quotes.
PS C:\> $moreheretext = @'
>> Here we go again
>> another line here
>> let's indent this
>>
>> a blank line above
>> '@
Note how the nested ' is handled OK, no double quoting needed.
PS C:\> $moreheretext
Here we go again
another line here
let's indent this
a blank line above
PS C:\>
To understand the importance of here strings, lets work with a multiple line string.
Without here strings
PS C:\> $sql = 'SELECT col1' `
>> + ' , col2' `
>> + ' , col3' `
>> + ' FROM someTable ' `
>> + ' WHERE col1 = ''a value'' '
PS C:\>
PS C:\> $sql
SELECT col1 , col2 , col3 FROM someTable WHERE col1 = 'a value'
With here strings
PS C:\> $sql = @'
>> SELECT col1
>> , col2
>> , col3
>> FROM someTable
>> WHERE col1 = 'a value'
>> '@
PS C:\> $sql
SELECT col1
, col2
, col3
FROM someTable
WHERE col1 = 'a value'
PS C:\> Set-Location C:\Python27\Scripts\
Take the output of Get-ChildItem, which is an object, and gets that objects count property.
PS C:\Python27\Scripts> $items = (Get-ChildItem).Count
PS C:\Python27\Scripts> $items
207
Take the output of Get-Location and store it in a variable.
PS C:\Python27\Scripts> $loc = Get-Location
PS C:\Python27\Scripts> $loc
Path
----
C:\Python27\Scripts
Use these variables in a string
PS C:\Python27\Scripts> "There are $items items are in the folder $loc."
There are 207 items are in the folder C:\Python27\Scripts.
To actually display the variable, escape it with a backtick,
PS C:\Python27\Scripts> "There are `$items items are in the folder `$loc."
There are $items items are in the folder $loc.
String interpolation only works with double quotes
PS C:\Python27\Scripts> 'There are $items items are in the folder $loc.'
There are $items items are in the folder $loc.
String Interpolation works with here strings
PS C:\Python27\Scripts> $hereinterpolation = @"
>> Items`tFolder
>> -----`t----------------------
>> $items`t`t$loc
>>
>> "@
PS C:\Python27\Scripts> $hereinterpolation
Items Folder
----- ----------------------
207 C:\Python27\Scripts
PS C:\Python27\Scripts> $hereinterpolation = @'
>> Items`tFolder
>> -----`t----------------------
>> $items`t`t$loc
>>
>> '@
PS C:\Python27\Scripts>
PS C:\Python27\Scripts> $hereinterpolation
Items`tFolder
-----`t----------------------
$items`t`t$loc
Observe that it didn't work for here strings defined with single quotes.
Expressions used within strings, need to be wrapped in $().
PS C:\Python27\Scripts> "There are $((Get-ChildItem).Count) items are in the folder $(Get-Location)."
There are 207 items are in the folder C:\Python27\Scripts.
PS C:\Python27\Scripts> "Today is $(Get-Date). Be well."
Today is 05/03/2017 12:43:17. Be well.
PS C:\Python27\Scripts> "The 15% tip of a 33.33 dollar bill is $(33.33 * 0.15) dollars"
The 15% tip of a 33.33 dollar bill is 4.9995 dollars
String Formatting - C# like syntax is supported. In C# you'd use:
PS C:\Python27\Scripts> [string]::Format("There are {0} items.", $items)
There are 207 items.
Powershell shortcut
PS C:\Python27\Scripts> "There are {0} items." -f $items
There are 207 items.
PS C:\Python27\Scripts> "There are {0} items in the location {1}." -f $items, $loc
There are 207 items in the location C:\Python27\Scripts.
PS C:\Python27\Scripts> "There are {0} items in the location {1}. Wow, {0} is a lot of items!" -f $items, $loc
There are 207 items in the location C:\Python27\Scripts. Wow, 207 is a lot of items!
- N - Numbers
- C - Currency
- P - Percentage
- X - Hex
- D - Decimal
N - Number
PS C:\> "N0 {0:N0} formatted" -f 12345678.119
N0 12,345,678 formatted
PS C:\> "N1 {0:N1} formatted" -f 12345678.119
N1 12,345,678.1 formatted
PS C:\> "N2 {0:N2} formatted" -f 12345678.119
N2 12,345,678.12 formatted
PS C:\> "N2 {0:N9} formatted" -f 12345678.119
N2 12,345,678.119000000 formatted
PS C:\> "N0 {0:N0} formatted" -f 123.119
N0 123 formatted
PS C:\> "N0 {0,8:N0} formatted" -f 123.119
N0 123 formatted
C - Currency
PS C:\> "C0 {0:C0} formatted" -f 12345678.1234
C0 $12,345,678 formatted
PS C:\> "C1 {0:C1} formatted" -f 12345678.1234
C1 $12,345,678.1 formatted
PS C:\> "C2 {0:C2} formatted" -f 12345678.1234
C2 $12,345,678.12 formatted
P - Percentage
PS C:\> "P0 {0:P0} formatted" -f 0.1234
P0 12 % formatted
PS C:\> "P2 {0:P2} formatted" -f 0.1234
P2 12.34 % formatted
X - Hex
PS C:\> "X0 0x{0:X0} formatted" -f 1234
X0 0x4D2 formatted
PS C:\> "X0 0x{0:X0} formatted" -f 0x4D2
X0 0x4D2 formatted
D - Decimal
PS C:\> "D0 {0:D0} formatted" -f 12345678
D0 12345678 formatted
PS C:\> "D8 {0:D8} formatted" -f 123
D8 00000123 formatted
PS C:\> "D0 {0:D0} formatted" -f 123
D0 123 formatted
PS C:\> "D0 {0,8:D0} formatted" -f 123
D0 123 formatted
Note, decimal only supports ints. This causes an error:
PS C:\> "D0 {0:D0} formatted" -f 123.1
Error formatting a string: Format specifier was invalid..
At line:1 char:1
+ "D0 {0:D0} formatted" -f 123.1
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (D0 {0:D0} formatted:String) [], RuntimeExcep
+ FullyQualifiedErrorId : FormatError
PS C:\> $items = 1234
PS C:\> "There are {0:#,#0} items." -f $items
There are 1,234 items.
PS C:\> "Custom 0, 25 $#,##0.0000 = {0,25:$ #,##0.0000} " -f 123456789.012000005
Custom 0, 25 $#,##0.0000 = $ 123,456,789.0120
PS C:\> "Custom 0, 25 $#,##0.0000 = {0,25:$ #,##0.00} " -f 123456789.012000005
Custom 0, 25 $#,##0.0000 = $ 123,456,789.01
PS C:\> "Custom 0, 25 $#,##0.0000 = {0,25:$ #,##0.00} " -f 123456789.012000005
Custom 0, 25 $#,##0.0000 = $ 123,456,789.01
PS C:\> "Custom 0, 10 #,##0% = {0,10:#,##0%} " -f 0.125
Custom 0, 10 #,##0% = 13%
PS C:\> "Custom 0, 10 #,##0.00% = {0,10:#,##0.00%} " -f 0.125
Custom 0, 10 #,##0.00% = 12.50%
PS C:\>
- MM - Month
- mm - minute
Custom date formatting. Note MM is Month, mm is minute
PS C:\> "Today is {0:M/d/yyyy}. Be well." -f $(Get-Date) # Today is 3/13/2014. Be well.
Today is 5-3-2017. Be well.
PS C:\> "Today is {0,10:MM/dd/yyyy}. Be well." -f $(Get-Date) # Today is 03/13/2014. Be well.
Today is 05-03-2017. Be well.
PS C:\> "Today is {0,10:yyyyMMdd}. Be well." -f $(Get-Date) # Today is 20140313. Be well.
Today is 20170503. Be well.
PS C:\> "Today is {0,10:MM/dd/yyyy hh:mm:ss}. Be well." -f $(Get-Date) # Today is 03/13/2014 12:21:19. Be well.
Today is 05-03-2017 03:51:54. Be well.
Calculations can be passed in as the item to be formatted
PS C:\> "The 20% tip of a 33.33 dollar bill is {0} dollars" -f (33.33 * 0.20) # The 20% tip of a 33.33 dollar bill is 6.666 dollars
The 20% tip of a 33.33 dollar bill is 6.666 dollars
PS C:\> "The 20% tip of a 33.33 dollar bill is {0:0.00} dollars" -f (33.33 * 0.20) # The 20% tip of a 33.33 dollar bill is 6.67 dollars
The 20% tip of a 33.33 dollar bill is 6.67 dollars
- It works using Wildcards
PS C:\> "PowerShell" -like "Power*"
True
PS C:\> "PowerShell" -like "Python*"
False
PS C:\> "PowerShell" -like "?owerShell" # question marks work for single characters
True
PS C:\> "PowerShell" -like "Power*[s-v]" # ends in a char between s and v
False
PS C:\> "PowerShell" -like "Power*[a-c]" # ends in a char between a and c
False
- It works using Regular Expressions
PS C:\> "888-368-1240" -match "[0-9]{3}-[0-9]{3}-[0-9]{4}"
True
PS C:\> "ZZZ-368-1240" -match "[0-9]{3}-[0-9]{3}-[0-9]{4}"
False
PS C:\> "888.368.1240" -match "[0-9]{3}-[0-9]{3}-[0-9]{4}"
FalseCreating Array(s)
PS C:\> $array = "Narendra", "Bhahubali"
PS C:\> $array
Narendra
Bhahubali
PS C:\> $array[0]
Narendra
PS C:\> $array[1]
Bhahubali
PS C:\> $array.GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Object[] System.Array Updating Array(s)
PS C:\> $array = "Barack", "Obama"
PS C:\> $array
Barack
Obama
PS C:\> $array[0] = "Power"
PS C:\> $array[1] = "Shell"
PS C:\> $array
Power
Shell
Formal Array Creation Syntax
PS C:\> $array = @("Power", "Shell")
PS C:\> $array
Power
Shell
Only way to create an empty array
PS C:\> $array = @()
PS C:\> $array.Count
0
PS C:\> $array += "jeffrey"
PS C:\> $array += "snover"
PS C:\> $array.Count
2
PS C:\> $array
jeffrey
snover
PS C:\> $array = 1..5 # Can load arrays using numeric range notation
PS C:\> $array
1
2
3
4
5
PS C:\>
PS C:\> # Check to see if an item exists
PS C:\> $numbers = 1, 42, 256
PS C:\> $numbers -contains 42
True
PS C:\> $numbers -notcontains 99
True
PS C:\> $numbers -notcontains 42
False
Load four individual arrays
PS C:\> $a = 1..5
PS C:\> $b = 6..10
PS C:\> $c = 11..15
PS C:\> $d = 16..20
PS C:\> write-Host "`$a = $a `n`$b = $b `n`$c = $c `n`$d = $d"
$a = 1 2 3 4 5
$b = 6 7 8 9 10
$c = 11 12 13 14 15
$d = 16 17 18 19 20
Now create an array from the four individual ones
PS C:\> $array = $a, $b, $c, $d
PS C:\> $array
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Array will now look like
Col [0] [1] [2] [3] [4]
Row [0] 1 2 3 4 5
Row [1] 6 7 8 9 10
Row [2] 11 12 13 14 15
Row [3] 16 17 18 19 20
Reference the second item in the second array (remember arrays are 0 based)
PS C:\> $array[1][2] # Zero based array, go to 2nd row, 3rd item
8
Take the contents of the array and join them into a single string.
PS C:\> $array[0] -join " "
1 2 3 4 5
PS C:\> $array[2] -join ” “
11 12 13 14 15
PS C:\> $array[3] -join ” “
16 17 18 19 20
PS C:\> $array[1][1]
7
PS C:\> $array[3][3]
19
PS C:\> $hash = @{"Key" = "Value";
"PowerShell" = "PowerShell.com";
"jeffrey snover" = "PowerShell Inventor"}
PS C:\> $hash # Display all values
Name Value
---- -----
PowerShell PowerShell.com
Key Value
jeffrey snover PowerShell Inventor By default, the hashes doesn't store the keys in the order of assignment. If we need to retain the assigned order,
PS C:\> $hash1 = [ordered]@{"Key" = "Value";
>> "PowerShell" = "PowerShell.com";
>> "jeffrey snover" = "PowerShell Inventor"}
>>
PS C:\> $hash1
Name Value
---- -----
Key Value
PowerShell PowerShell.com
jeffrey snover PowerShell Inventor
Values from hash key can be retrieved in two ways:
PS C:\> $hash["PowerShell"] # Get a single value from the key
PowerShell.com
PS C:\> $hash."jeffrey snover" # Get single value using object syntax
PowerShell Inventor
You can use variables as keys
PS C:\> $mykey = "PowerShell"
PS C:\> $hash.$mykey # Using variable as a property
PowerShell.com
PS C:\> $hash.$($mykey) # Evaluating as an expression
PowerShell.com
PS C:\> $hash.$("Power" + "Shell")
PowerShell.com
Adding and removing values
PS C:\> $hash # Here's what's there to start
Name Value
---- -----
PowerShell PowerShell.com
Key Value
jeffrey snover PowerShell Inventor
PS C:\> $hash["aws"] = "Amazon Web Services" # Add value using new key
PS C:\> $hash # Show the additional row
Name Value
---- -----
PowerShell PowerShell.com
aws Amazon Web Services
Key Value
jeffrey snover PowerShell Inventor
PS C:\> $hash.Remove("jeffrey snover") # Remove by passing in key
PS C:\> $hash
Name Value
---- -----
PowerShell PowerShell.com
aws Amazon Web Services
Key Value
See if key exists
PS C:\> $hash.Contains("aws") # Should be there
True
PS C:\> $hash.Contains("jeffrey snover") # Gone since we just removed it
False
See if value exists
PS C:\> $hash.ContainsValue("PowerShell.com") # Will be there
True
PS C:\> $hash.ContainsValue("PowerShell Inventor") # Not there since it was removed
False
List keys and values
PS C:\> $hash.Keys
PowerShell
aws
Key
PS C:\> $hash.Values
PowerShell.com
Amazon Web Services
Value
Find if a key or value is present
PS C:\> $hash.Keys -contains "PowerShell"
True
PS C:\> $hash.Values -contains "PowerShell.com"
True
PS C:\> $var = 2
if ($var -eq 1) # Be sure to use -eq instead of =
{
"If branch"
}
else
{
"else branch"
}
else branchPS C:\> $var = 2
if ($var -eq 1)
{
"If -eq 1 branch"
}
elseif ($var -eq 2)
{
"ElseIf -eq 2 branch"
}
else
{
"else branch"
}
ElseIf -eq 2 branchPS C:\> # Switch statement for multiple conditions
$var = 42 # Also test with 43 and 49
switch ($var)
{
41 {"Forty One"}
42 {"Forty Two"}
43 {"Forty Three"}
default {"default"}
}
Forty Two
PS C:\> # Will match all lines that match
PS C:\> $var = 42
switch ($var)
{
42 {"Forty Two"}
"42" {"Forty Two String"}
default {"default"}
}
Forty Two
Forty Two StringNote that type coercion will cause both 42 lines to have a match.
To stop processing once a block is found use break
PS C:\> $var = 42
switch ($var)
{
42 {"Forty Two"; break}
"42" {"Forty Two String"; break}
default {"default"}
}
Forty Two
Note, if you want to put multiple commands on a single line, use a ; to separate them
Switch works with collections, looping and executing for each match
PS C:\> switch (3,1,2,42)
{
1 {"One"}
2 {"Two"}
3 {"Three"}
default {"The default answer"}
}
Three
One
Two
The default answer
String compares are case insensitive by default
PS C:\> switch ("PowerShell")
{
"powershell" {"lowercase"}
"POWERSHELL" {"uppercase"}
"PowerShell" {"mixedcase"}
}
lowercase
uppercase
mixedcase
Use the -casesenstive switch to make it so
PS C:\> switch -casesensitive ("PowerShell")
{
"powershell" {"lowercase"}
"POWERSHELL" {"uppercase"}
"PowerShell" {"mixedcase"}
}
mixedcase
Supports wildcards
PS C:\> switch -Wildcard ("Pluralsight")
{
"plural*" {"*"}
"?luralsight" {"?"}
"Pluralsi???" {"???"}
}
*
?
???
Note that it will also support regex matches.
PS C:\> # While
$i = 1
while ($i -le 5)
{
"`$i = $i"
$i = $i + 1
}
$i = 1
$i = 2
$i = 3
$i = 4
$i = 5
PS C:\> # While won't execute if condition is already true
$i = 6
while ($i -le 5)
{
"`$i = $i"
$i = $i + 1
}
PS C:\> # do-while
$i = 1
do
{
"`$i = $i"
$i++
} while($i -le 5)
$i = 1
$i = 2
$i = 3
$i = 4
$i = 5
Do will always execute at least once
$i = 6
do
{
"`$i = $i"
$i++
} while($i -le 5)
$i = 6
Use until to make the check more positive
$i = 1
do
{
"`$i = $i"
$i++
} until($i -gt 5)
$i = 1
$i = 2
$i = 3
$i = 4
$i = 5
PS C:\> for ($f = 0; $f -le 5; $f++)
{
"`$f = $f"
}
$f = 0
$f = 1
$f = 2
$f = 3
$f = 4
$f = 5Note the initializer can be set seperately
PS C:\> $f = 2
for (; $f -le 5; $f++)
{
"`$f = $f"
}
$f = 2
$f = 3
$f = 4
$f = 5
Iterating over a collection 1 by 1
PS C:\> $array = 11,12,13,14,15 # Simple Array
for ($i=0; $i -lt $array.Length; $i++)
{
"`$array[$i]=" + $array[$i]
}
$array[0]=11
$array[1]=12
$array[2]=13
$array[3]=14
$array[4]=15
foreach works on a collection
PS C:\> $array = 11,12,13,14,15 # Simple Array
foreach ($item in $array)
{
"`$item = $item"
}
$item = 11
$item = 12
$item = 13
$item = 14
$item = 15
PS C:\> "1KB=$(1KB)"
1KB=1024
PS C:\> "1MB=$(1MB)"
1MB=1048576
PS C:\> "1GB=$(1GB)"
1GB=1073741824
PS C:\> "1TB=$(1TB)"
1TB=1099511627776
PS C:\> "1PB=$(1PB)"
1PB=1125899906842624
PS C:\> foreach($i in @('1KB', '1MB', '1GB', '1TB', '1PB')){Write-Host "$i =$($i)"}
1KB =1KB
1MB =1MB
1GB =1GB
1TB =1TB
1PB =1PB
foreach works with an array of objects
PS C:\> foreach ($file in Get-ChildItem -Path "C:\Python27")
{
$file.Name
}
DLLs
Doc
etc
include
Lib
libs
Scripts
share
tcl
Tools
LICENSE.txt
NEWS.txt
python.exe
pythonw.exe
README.txt
w9xpopen.exe
Use break to get out of the loop
PS C:\> foreach ($file in Get-ChildItem -Path "C:\Python27")
{
if ($file.Name -like "*.exe")
{
$file.Name
break # exits the loop on first hit
}
}
python.exe
Use continue to skip the rest of a loop but go onto the next iteration
PS C:\> foreach ($file in Get-ChildItem -Path "C:\Python27")
{
if ($file.Name -like "*.exe")
{
$file.Name
continue # exits the loop on first hit
"More code here"
}
"This isn't a executable file: $file"
}
This isn't a executable file: DLLs
This isn't a executable file: Doc
This isn't a executable file: etc
This isn't a executable file: include
This isn't a executable file: Lib
This isn't a executable file: libs
This isn't a executable file: Scripts
This isn't a executable file: share
This isn't a executable file: tcl
This isn't a executable file: Tools
This isn't a executable file: LICENSE.txt
This isn't a executable file: NEWS.txt
python.exe
pythonw.exe
This isn't a executable file: README.txt
w9xpopen.exe
When used in a nested loop, break exits to the outer loop
PS C:\> foreach ($outside in 1..3)
{
"`$outside=$outside"
foreach ($inside in 4..6)
{
" `$inside = $inside"
break
}
}
$outside=1
$inside = 4
$outside=2
$inside = 4
$outside=3
$inside = 4
Use loop labels to break to a certain loop
PS C:\> :outsideloop foreach ($outside in 1..3)
{
"`$outside=$outside"
foreach ($inside in 4..6)
{
" `$inside = $inside"
break outsideloop
}
}
$outside=1
$inside = 4
Using continue inside an inner loop
foreach ($outside in 1..3)
{
"`$outside=$outside"
foreach ($inside in 4..6)
{
" `$inside = $inside"
continue
"this will never execute as continue goes back to start of inner for loop"
# note, because we continue to the inside loop, the above line
# will never run but it will go thru all iterations of the inner loop
}
}
$outside=1
$inside = 4
$inside = 5
$inside = 6
$outside=2
$inside = 4
$inside = 5
$inside = 6
$outside=3
$inside = 4
$inside = 5
$inside = 6
PS C:\> :outsideloop foreach ($outside in 1..3)
{
"`$outside=$outside"
foreach ($inside in 4..6)
{
" `$inside = $inside"
continue outsideloop
"this will never execute as continue goes back to start of inner for loop"
# here, because we break all the way to the outer loop the last two
# iterations (5 and 6) never run
}
"some more stuff here that will never run"
}
$outside=1
$inside = 4
$outside=2
$inside = 4
$outside=3
$inside = 4
A basic script block is code inside {}. The for (as well as other loops) execute a script block.
PS C:\> for ($f = 0; $f -le 5; $f++)
{
"`$f = $f"
}
$f = 0
$f = 1
$f = 2
$f = 3
$f = 4
$f = 5PS C:\> for ($f = 0; $f -le 5; $f++)
{
"`$f = $f"
}
$f = 0
$f = 1
$f = 2
$f = 3
$f = 4
$f = 5A script block can exist on its own.
NOTE: To put multiple commands on a single line use the ;
PS C:\> {Clear-Host; "Powershell is cool."}
Clear-Host; "Powershell is cool."Executing only shows the contents of the block, doesn't execute it.
To actually run it, use an ampersand & in front.
PS C:\> &{Clear-Host; "Powershell is cool."}
Powershell is cool.
You can store script blocks inside a variable
PS C:\> $cool = {Clear-Host; "Powershell is cool."}
Just entering the variable though only shows the contents, doesn't run it.
PS C:\>Clear-Host; "Powershell is cool."
PS C:\> & $cool # To actually run it, use the & character
Powershell is cool.
Since scripts can be put in a variable, you can do interesting things.
PS C:\> $cool = {"Powershell is cool."; " So is jeffrey snover"}
for ($i=0;$i -lt 3; $i++)
{
&$cool;
}
Powershell is cool.
So is jeffrey snover
Powershell is cool.
So is jeffrey snover
Powershell is cool.
So is jeffrey snover
PS C:\> $hw = {
"Hello World"
}
PS C:\> & $hw
Hello WorldFunctions are basically script blocks with names.
PS C:\> function Write-HelloWorld()
{
"Hello World"
}Running the above simply places the function in memory for us to use. To use it, call it like you would a cmdlet.
PS C:\> Write-HelloWorld
Hello World
When writing functions, use an approved verb. To get the list of approved verbs,
PS C:\> Get-Verb
Verb Group
---- -----
Add Common
Clear Common
Close Common
Copy Common
Enter Common
Exit Common
Find Common
Format Common
Get Common
Hide Common
Join Common
Lock Common
Move Common
New Common
Open Common
Optimize Common
Pop Common
Push Common
Redo Common
Remove Common
Rename Common
Reset Common
Resize Common
Search Common
Select Common
Set Common
Show Common
Skip Common
Split Common
Step Common
Switch Common
Undo Common
Unlock Common
Watch Common
Backup Data
Checkpoint Data
Compare Data
Compress Data
Convert Data
ConvertFrom Data
ConvertTo Data
Dismount Data
Edit Data
Expand Data
Export Data
Group Data
Import Data
Initialize Data
Limit Data
Merge Data
Mount Data
Out Data
Publish Data
Restore Data
Save Data
Sync Data
Unpublish Data
Update Data
Approve Lifecycle
Assert Lifecycle
Complete Lifecycle
Confirm Lifecycle
Deny Lifecycle
Disable Lifecycle
Enable Lifecycle
Install Lifecycle
Invoke Lifecycle
Register Lifecycle
Request Lifecycle
Restart Lifecycle
Resume Lifecycle
Start Lifecycle
Stop Lifecycle
Submit Lifecycle
Suspend Lifecycle
Uninstall Lifecycle
Unregister Lifecycle
Wait Lifecycle
Debug Diagnostic
Measure Diagnostic
Ping Diagnostic
Repair Diagnostic
Resolve Diagnostic
Test Diagnostic
Trace Diagnostic
Connect Communications
Disconnect Communications
Read Communications
Receive Communications
Send Communications
Write Communications
Block Security
Grant Security
Protect Security
Revoke Security
Unblock Security
Unprotect Security
Use Other Parameters can be passed in by placing them in parenthesis.
PS C:\> function Get-Fullname($firstName, $lastName)
{
Write-Host ($firstName + " " + $lastName)
}Note: when calling the function with parameters, do not use commas or ().
PS C:\> function Get-Fullname($firstName, $lastName)
{
Write-Host ($firstName + " " + $lastName)
}
PS C:\> Get-Fullname "jeffrey" "snover"
jeffrey snover
PS C:\>
PS C:\> $myVar = "jeffrey"
PS C:\> Get-Fullname $myVar "snover"
jeffrey snover
PS C:\> Get-Fullname $("je" + "ffrey") "snover"
jeffrey snoverAny changes to a paramater inside a function are scoped to that function.
PS C:\> function Set-NonRefVar($myparam)
{
$myparam = 33
"Inside function `$myparam = $myparam"
}
PS C:\> $myparam = 42
PS C:\> "Prior to funciton `$myparam = $myparam"
Prior to funciton $myparam = 42
PS C:\> Set-NonRefVar($myparam)
Inside function $myparam = 33
PS C:\> "After funciton `$myparam = $myparam"
After funciton $myparam = 42To change a value inside a funciton, use [ref]
Passing by reference simply requires a [ref] tag before the variable
Note however it turns it into an object, thus requiring the .Value syntax.
PS C:\> function Set-RefVar([ref] $myparam)
{
$myparam.Value = 33
"Inside function `$myparam = $($myparam.Value)"
}
PS C:\> $myparam = 42
PS C:\> "Prior to funciton `$myparam = $myparam"
Prior to funciton $myparam = 42
PS C:\> Set-RefVar ([ref] $myparam) # Must add ref to call
Inside function $myparam = 33
PS C:\> "After funciton `$myparam = $myparam"
After funciton $myparam = 33NOTE: Altering the value of parameters is considered poor programming practice and should be avoided. Instead use return.
PS C:\> function Get-AValue($one, $two)
{
return $one * $two
}
PS C:\> Get-AValue 33 42
1386
PS C:\> $returnValue = Get-AValue 33 42
PS C:\> "Returned value is $returnValue"
Returned value is 1386Functions also support named parameters. Simply put the name of the parameter with a -
PS C:\> $returnValue = Get-AValue -one 33 -two 42
PS C:\> "Returned value is $returnValue"
Returned value is 1386
With named parameters, order is no longer important.
PS C:\> $returnValue = Get-AValue -two 42 -one 33
PS C:\> "Returned value is $returnValue"
Returned value is 1386
It is possible to pipeline enable your functions. These are referred to as advanced functions.
PS C:\> function Get-EXEFiles ()
{
# The begin block executes once at the start of the function
begin { $retval = "Here are some EXE files: `r`n" }
# The process block is executed once for each object being
# passed in from the pipe
process {
if ($_.Name -like "*.exe")
{
$retval += "`t$($_.Name)`r`n"
# Note this line could also be rendered as
# $retval = $retval + "`t" + $_.Name + "`r`n"
# `t Tab Character
# `r Carriage Return
# `n Line Feed
# $( ) Tells PS to evaute the expression in () first then return it
# $_ The current object being passed in the pipeline
# .Name The name property of the current object
}
}
# The end block executes once, after the rest of the function
end { return $retval }
}
PS C:\> Get-ChildItem -Path "C:\Python27\" | Get-EXEFiles
Here are some EXE files:
python.exe
pythonw.exe
Removecx_Oracle.exe
w9xpopen.exe
PS C:\> $output = Get-ChildItem | Get-EXEFiles
PS C:\> $output.GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True String System.Object
PS C:\> $i = 0
foreach($f in $output)
{
$i++
"$i : $f"
}
1 : Here are some EXE files:
To pipeline the output, push the output in the process area.
PS C:\> function Get-EXEFiles ()
{
begin { }
process {
if ($_.Name -like "*.exe")
{
$retval = "`tEXE file is $($_.Name)"
$retval # This is the equivalent of: return $retval
}
}
end { }
}
PS C:\> $output = Get-ChildItem -Path "C:\Python27" | Get-EXEFiles
PS C:\> $output.GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Object[] System.Array
PS C:\> $i = 0
PS C:\> foreach($f in $output)
{
$i++
"$i : $f"
}
1 : EXE file is python.exe
2 : EXE file is pythonw.exe
3 : EXE file is Removecx_Oracle.exe
4 : EXE file is w9xpopen.exe
PS C:\>
PS C:\> function Write-SomeText ()
{
# begin { }
process {
$retval = "Here is the output: $($_)"
$retval
}
# end { }
}
PS C:\> Get-ChildItem -Path "C:\Python27" | Get-EXEFiles | Write-SomeText
Here is the output: EXE file is python.exe
Here is the output: EXE file is pythonw.exe
Here is the output: EXE file is Removecx_Oracle.exe
Here is the output: EXE file is w9xpopen.exeSimilar to original function but truly pipelined.
PS C:\> "Here are some PowerShell files: `r`n"
Here are some PowerShell files:
PS C:\> Get-ChildItem -Path "C:\Python27"| Get-PSFiles
Here are some PowerShell files:
Advanced functions also allow parameters with extra helping hints.
PS C:\> function Get-AValue ()
{
[CmdletBinding()] # Needed to indicate this is an advanced function
param ( # Begin the parameter block
[Parameter( Mandatory = $true,
HelpMessage = 'Please enter value one.'
)]
[int] $one,
# Note in the second we are strongly typing, and are providing a default value
[Parameter( Mandatory = $false,
HelpMessage = 'Please enter value two.'
)]
[int] $two = 42
) # End the parameter block
begin { }
process {
return $one * $two
}
end { }
}Example 1: pass in values
PS C:\> Get-AValue -one 33 -two 42
1386Example 2: pass in value for one, take default for two
PS C:\> Get-AValue -one 33
1386Example 3: no params, will prompt for one and take default for two
PS C:\> Get-AValue
cmdlet Get-AValue at command pipeline position 1
Supply values for the following parameters:
(Type !? for Help.)
one: 33
1386Example 4: use a string for one (generates error)
PS C:\> Get-AValue -one "x"
Get-AValue : Cannot process argument transformation on parameter 'one'. Cannot
convert value "x" to type "System.Int32". Error: "Input string was not in a
correct format."
At line:1 char:17
+ Get-AValue -one "x"
+ ~~~
+ CategoryInfo : InvalidData: (:) [Get-AValue], ParameterBindingA
rgumentTransformationException
+ FullyQualifiedErrorId : ParameterArgumentTransformationError,Get-AValuePowerShell is possessing a robust cmdlet for help
PS C:\> Get-Help Get-ChildItem
NAME
Get-ChildItem
SYNTAX
Get-ChildItem [[-Path] <string[]>] [[-Filter] <string>] [-Include
<string[]>] [-Exclude <string[]>] [-Recurse] [-Depth <uint32>] [-Force]
[-Name] [-UseTransaction] [-Attributes <FlagsExpression[FileAttributes]>
{ReadOnly | Hidden | System | Directory | Archive | Device | Normal |
Temporary | SparseFile | ReparsePoint | Compressed | Offline |
NotContentIndexed | Encrypted | IntegrityStream | NoScrubData}]
[-Directory] [-File] [-Hidden] [-ReadOnly] [-System] [<CommonParameters>]
Get-ChildItem [[-Filter] <string>] -LiteralPath <string[]> [-Include
<string[]>] [-Exclude <string[]>] [-Recurse] [-Depth <uint32>] [-Force]
[-Name] [-UseTransaction] [-Attributes <FlagsExpression[FileAttributes]>
{ReadOnly | Hidden | System | Directory | Archive | Device | Normal |
Temporary | SparseFile | ReparsePoint | Compressed | Offline |
NotContentIndexed | Encrypted | IntegrityStream | NoScrubData}]
[-Directory] [-File] [-Hidden] [-ReadOnly] [-System] [<CommonParameters>]
ALIASES
gci
ls
dir
REMARKS
Get-Help cannot find the Help files for this cmdlet on this computer. It
is displaying only partial help.
-- To download and install Help files for the module that includes
this cmdlet, use Update-Help.
-- To view the Help topic for this cmdlet online, type: "Get-Help
Get-ChildItem -Online" or
go to http://go.microsoft.com/fwlink/?LinkID=113308.Help for our function
PS C:\> function Get-ChildName ()
{
Write-Output (Get-ChildItem | Select-Object "Name")
}
PS C:\> Get-Help Get-ChildName
NAME
Get-ChildName
SYNTAX
Get-ChildName
ALIASES
None
REMARKS
NoneCustom tags within a comment block that Get-Help will recognize
Note that not all of them are required
.SYNOPSIS - A brief description of the command
.DESCRIPTION - Detailed command description
.PARAMETER name - Include one description for each parameter
.EXAMPLE - Detailed examples on how to use the command
.INPUTS - What pipeline inputs are supported
.OUTPUTS - What this funciton outputs
.NOTES - Any misc notes you haven't put anywhere else
.LINK - A link to the URL for more help. Use one .LINK tag per URL
Use "Get-Help about_comment_based_help" for full list and details
PS C:\> function Get-ChildName ()
{
<#
.SYNOPSIS
Returns a list of only the names for the child items in the current location.
.DESCRIPTION
This function is similar to Get-ChildItem, except that it returns only the name
property.
.INPUTS
None.
.OUTPUTS
System.String. Sends a collection of strings out the pipeline.
.EXAMPLE
Example 1 - Simple use
Get-ChildName
.EXAMPLE
Example 2 - Passing to another object in the pipeline
Get-ChildName | Where-Object {$_.Name -like "*.ps1"}
.LINK
Get-ChildItem
#>
Write-Output (Get-ChildItem | Select-Object "Name")
}PS C:\> Get-Help Get-ChildName
NAME
Get-ChildName
SYNOPSIS
Returns a list of only the names for the child items in the current
location.
SYNTAX
Get-ChildName [<CommonParameters>]
DESCRIPTION
This function is similar to Get-ChildItem, except that it returns only the
name
property.
RELATED LINKS
Get-ChildItem
REMARKS
To see the examples, type: "get-help Get-ChildName -examples".
For more information, type: "get-help Get-ChildName -detailed".
For technical information, type: "get-help Get-ChildName -full".
For online help, type: "get-help Get-ChildName -online"
PS C:\> Get-Help Get-ChildName -full
NAME
Get-ChildName
SYNOPSIS
Returns a list of only the names for the child items in the current
location.
SYNTAX
Get-ChildName [<CommonParameters>]
DESCRIPTION
This function is similar to Get-ChildItem, except that it returns only the
name
property.
PARAMETERS
<CommonParameters>
This cmdlet supports the common parameters: Verbose, Debug,
ErrorAction, ErrorVariable, WarningAction, WarningVariable,
OutBuffer, PipelineVariable, and OutVariable. For more information,
see
about_CommonParameters
(http://go.microsoft.com/fwlink/?LinkID=113216).
INPUTS
None.
OUTPUTS
System.String. Sends a collection of strings out the pipeline.
-------------------------- EXAMPLE 1 --------------------------
PS C:\>Example 1 - Simple use
Get-ChildName
-------------------------- EXAMPLE 2 --------------------------
PS C:\>Example 2 - Passing to another object in the pipeline
Get-ChildName | Where-Object {$_.Name -like "*.ps1"}
RELATED LINKS
Get-ChildItem Better Error handling is essential for managing the scripts.
PS C:\> function divver($enum,$denom)
{
Write-Host "Divver begin."
$result = $enum / $denom
Write-Host "Result: $result"
Write-Host "Divver done."
}
PS C:\> divver 33 3 # No Error
Divver begin.
Result: 11
Divver done.
PS C:\> divver 33 0 # Generates Error
Divver begin.
Attempted to divide by zero.
At line:4 char:3
+ $result = $enum / $denom
+ ~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], RuntimeException
+ FullyQualifiedErrorId : RuntimeException
Result:
Divver done.Handle errors using try/catch/finally
PS C:\> function divver($enum,$denom)
{
Write-Host "Divver begin."
try
{
$result = $enum / $denom
Write-Host "Result: $result"
}
catch
{
Write-Host "Oh NO! An error has occurred!!"
Write-Host $_.ErrorID
Write-Host $_.Exception.Message
break # With break, or omitting it, error bubbles up to parent
}
finally
{
Write-Host "Divver done."
}
}
PS C:\> divver 33 3 # No Error
Divver begin.
Result: 11
Divver done.
PS C:\> divver 33 0 # Generates Error
Divver begin.
Oh NO! An error has occurred!!
Attempted to divide by zero.
Divver done.The errors that occur mainly falls under two categories:
a. Terminating Errors halts the command (or script execution) completely.
Ex: non-existent cmdlets, syntax errors that would prevent a cmdlet from running, or other fatal errors.
b. Non-Terminating Errors allows execution to continue despite the failure.
Ex: operational errors such file not found, permissions problems, etc.
When either type of error occurs during execution, it is logged to a global variable called $Error. This variable is a collection of PowerShell error objects with the most recent error at index 0.
C:\> $Error.GetType()
Public IsSerial Name BaseType
------ -------- ---- --------
ue True ArrayList System.Object
C:\> $Error.Count
C:\> Some-Command
me-Command : The term 'Some-Command' is not recognized as the name of a cmdlet, function, script file, or operable
ogram. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
line:1 char:1
Some-Command
~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (Some-Command:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException
C:\> $Error.Count
C:\> $error[0]
me-Command : The term 'Some-Command' is not recognized as the name of a cmdlet, function, script file, or operable
ogram. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
line:1 char:1
Some-Command
~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (Some-Command:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException
C:\> $error[0] | Get-Member
TypeName: System.Management.Automation.ErrorRecord
me MemberType Definition
-- ---------- ----------
uals Method bool Equals(System.Object obj)
tHashCode Method int GetHashCode()
tObjectData Method void GetObjectData(System.Runtime.Serialization.SerializationInfo info, System....
tType Method type GetType()
String Method string ToString()
tegoryInfo Property System.Management.Automation.ErrorCategoryInfo CategoryInfo {get;}
rorDetails Property System.Management.Automation.ErrorDetails ErrorDetails {get;set;}
ception Property System.Exception Exception {get;}
llyQualifiedErrorId Property string FullyQualifiedErrorId {get;}
vocationInfo Property System.Management.Automation.InvocationInfo InvocationInfo {get;}
pelineIterationInfo Property System.Collections.ObjectModel.ReadOnlyCollection[int] PipelineIterationInfo {g...
riptStackTrace Property string ScriptStackTrace {get;}
rgetObject Property System.Object TargetObject {get;}
MessageDetails ScriptProperty System.Object PSMessageDetails {get=& { Set-StrictMode -Version 1; $this.Except...
C:\> $error[0].InvocationInfo
Command :
undParameters : {}
boundArguments : {}
riptLineNumber : 1
fsetInLine : 1
storyId : 5
riptName :
ne : Some-Command
sitionMessage : At line:1 char:1
+ Some-Command
+ ~~~~~~~~~~~~
ScriptRoot :
CommandPath :
vocationName : Some-Command
pelineLength : 0
pelinePosition : 0
pectingInput : False
mmandOrigin : Internal
splayScriptPosition :
C:\> $error[0].Exception
e term 'Some-Command' is not recognized as the name of a cmdlet, function, script file, or operable program. Check
e spelling of the name, or if a path was included, verify that the path is correct and try again.
C:\>
C:\> $error[0].Exception.StackTrace
at System.Management.Automation.CommandDiscovery.LookupCommandInfo(String commandName, CommandTypes commandTypes, Sea
hResolutionOptions searchResolutionOptions, CommandOrigin commandOrigin, ExecutionContext context)
at System.Management.Automation.CommandDiscovery.LookupCommandProcessor(String commandName, CommandOrigin commandOrig
, Nullable`1 useLocalScope)
at System.Management.Automation.ExecutionContext.CreateCommand(String command, Boolean dotSource)
at System.Management.Automation.PipelineOps.AddCommand(PipelineProcessor pipe, CommandParameterInternal[] commandElem
ts, CommandBaseAst commandBaseAst, CommandRedirection[] redirections, ExecutionContext context)
at System.Management.Automation.PipelineOps.InvokePipeline(Object input, Boolean ignoreInput, CommandParameterInterna
][] pipeElements, CommandBaseAst[] pipeElementAsts, CommandRedirection[][] commandRedirections, FunctionContext funcCo
ext)
at System.Management.Automation.Interpreter.ActionCallInstruction`6.Run(InterpretedFrame frame)
at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
C:\>PowerShell halts execution on terminating errors. Error Action Preference allows us to specify the desired behavior for a non-terminating error; it can be scoped at the command level or all the way up to the script level.
Available choices for error action preference:
- SilentlyContinue – error messages are suppressed and execution continues.
- Stop – forces execution to stop, behaving like a terminating error.
- Continue – the default option. Errors will display and execution will continue.
- Inquire – prompt the user for input to see if we should proceed.
- Ignore – (new in v3) – the error is ignored and not logged to the error stream. Has very restricted usage scenarios.
Example: Set the preference at the script scope to Stop, place the following near the top of the script file:
PS C:\> $ErrorActionPreference = “Stop”Example: Set the preference at the cmdlet level to Inquire, add error action switch (or alias EA):
PS C:\> Get-ChildItem "D:\No Such Directory" -ErrorAction "Inquire"
Confirm
Cannot find drive. A drive with the name 'D' does not exist.
[Y] Yes [A] Yes to All [H] Halt Command [S] Suspend [?] Help (default is "Y"): Y
Get-ChildItem : Cannot find drive. A drive with the name 'D' does not exist.
At line:1 char:1
+ Get-ChildItem "D:\No Such Directory" -ErrorAction "Inquire"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (D:String) [Get-ChildItem], DriveNotFoundException
+ FullyQualifiedErrorId : DriveNotFound,Microsoft.PowerShell.Commands.GetChildItemCommand
The behavior of try/catch is to catch terminating errors (exceptions). This means Non-terminating (operational) errors inside a try block will not trigger a Catch*. If you would like to catch all possible errors (terminating and non-terminating) – then simply set the error action preference to Stop. Remember that Stop error action forces a non-terminating error to behave like a terminating error, which means it can then be trapped in a catch block.
PS C:\> try
{
<#
Add dangerous code here that might produce exceptions.
Place as many code statements as needed here.
Non-terminating errors must have error action preference set to Stop to be caught.
#>
write-host “Attempting dangerous operation”
$content = get-content -Path “C:\SomeFolder\This_File_Might_Not_Exist.txt” -ErrorAction Stop
}
catch
{
<#
You can have multiple catch blocks (for different exceptions), or one single catch.
The last error record is available inside the catch block under the $_ variable.
Code inside this block is used for error handling. Examples include logging an error,
sending an email, writing to the event log, performing a recovery action, etc.
In this example I’m just printing the exception type and message to the screen.
#>
write-host “Caught an exception:” -ForegroundColor Red
write-host “Exception Type: $($_.Exception.GetType().FullName)” -ForegroundColor Red
write-host “Exception Message: $($_.Exception.Message)” -ForegroundColor Red
}
finally
{
<#
Any statements in this block will always run even if errors are caught.
This statement block is optional. Normally used for cleanup and
releasing resources that must happen even under error situations.
#>
write-host “Finally block reached”
}
Attempting dangerous operation
Caught an exception:
Exception Type: System.Management.Automation.ItemNotFoundException
Exception Message: Cannot find path 'C:\SomeFolder\This_File_Might_Not_Exist.txt
' because it does not exist.
Finally block reachedFinally block is option; but try and catch blocks are essential for handling exceptions.
PS C:\> write-Host $(1/0)
Attempted to divide by zero.
At line:1 char:14
+ write-Host $(1/0)
+ ~~~
+ CategoryInfo : NotSpecified: (:) [], RuntimeException
+ FullyQualifiedErrorId : RuntimeException
Catching this exception
PS C:\> try
{
write-Host $(1/0)
}
catch
{
write-Host "This is an Exception"
}
This is an ExceptionDisplaying the actual exception
PS C:\> try
{
write-Host $(1/0)
}
catch
{
write-Host $_.Exception
}
System.Management.Automation.RuntimeException: Attempted to divide by zero. --->
System.DivideByZeroException: Attempted to divide by zero.
--- End of inner exception stack trace ---
at System.Management.Automation.ExceptionHandlingOps.CheckActionPreference(Fu
nctionContext funcContext, Exception exception)
at System.Management.Automation.Interpreter.ActionCallInstruction`2.Run(Inter
pretedFrame frame)
at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.R
un(InterpretedFrame frame)
at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.R
un(InterpretedFrame frame)Handling the exception with the appropriate exception type:
PS C:\> try
{
write-Host $(1/0)
}
catch [System.Management.Automation.RuntimeException]
{
write-Host "This is Run-time Exception"
}
catch
{
write-Host "Other Exception"
}
This is Run-time Exception
To get all the exceptions
PS C:\> [appdomain]::CurrentDomain.GetAssemblies() | ForEach {
Try {
$_.GetExportedTypes() | Where {
$_.Fullname -match 'Exception'
}
} Catch {}
} | Select FullName
FullName
--------
System.AggregateException
System.Exception
System.SystemException
System.OutOfMemoryException
System.StackOverflowException
System.DataMisalignedException
System.ExecutionEngineException
System.MemberAccessException
System.AccessViolationException
System.ApplicationException
System.AppDomainUnloadedException
System.ArgumentException
System.ArgumentNullException
System.ArgumentOutOfRangeException
System.ArithmeticException
System.ArrayTypeMismatchException
System.BadImageFormatException
System.CannotUnloadAppDomainException
System.TypeUnloadedException
System.ContextMarshalException
System.DivideByZeroException
System.DuplicateWaitObjectException
System.EntryPointNotFoundException
System.DllNotFoundException
System.FieldAccessException
System.FormatException
System.IndexOutOfRangeException
System.InsufficientMemoryException
System.InsufficientExecutionStackException
System.InvalidCastException
System.InvalidOperationException
System.InvalidProgramException
System.InvalidTimeZoneException
System.MethodAccessException
System.MissingFieldException
System.MissingMemberException
System.MissingMethodException
System.MulticastNotSupportedException
System.NotFiniteNumberException
System.NotImplementedException
System.NotSupportedException
System.NullReferenceException
System.ObjectDisposedException
System.OperationCanceledException
System.OverflowException
System.PlatformNotSupportedException
System.RankException
System.TimeoutException
System.TimeZoneNotFoundException
System.TypeAccessException
System.TypeInitializationException
System.TypeLoadException
System.UnauthorizedAccessException
System.UnhandledExceptionEventArgs
System.UnhandledExceptionEventHandler
System.IO.DirectoryNotFoundException
System.IO.DriveNotFoundException
System.IO.EndOfStreamException
System.IO.FileLoadException
System.IO.FileNotFoundException
System.IO.IOException
System.IO.PathTooLongException
System.IO.IsolatedStorage.IsolatedStorageException
System.Security.XmlSyntaxException
System.Security.SecurityException
System.Security.HostProtectionException
System.Security.VerificationException
System.Security.AccessControl.PrivilegeNotHeldException
System.Security.Cryptography.CryptographicException
System.Security.Cryptography.CryptographicUnexpectedOperationException
System.Security.Principal.IdentityNotMappedException
System.Security.Policy.PolicyException
System.Resources.MissingManifestResourceException
System.Resources.MissingSatelliteAssemblyException
System.Globalization.CultureNotFoundException
System.Diagnostics.Tracing.EventSourceException
System.Collections.Generic.KeyNotFoundException
System.Threading.AbandonedMutexException
System.Threading.LockRecursionException
System.Threading.SemaphoreFullException
System.Threading.SynchronizationLockException
System.Threading.ThreadAbortException
System.Threading.ThreadInterruptedException
System.Threading.ThreadStateException
System.Threading.ThreadStartException
System.Threading.WaitHandleCannotBeOpenedException
System.Threading.Tasks.TaskCanceledException
System.Threading.Tasks.TaskSchedulerException
System.Threading.Tasks.UnobservedTaskExceptionEventArgs
System.Reflection.AmbiguousMatchException
System.Reflection.CustomAttributeFormatException
System.Reflection.InvalidFilterCriteriaException
System.Reflection.ExceptionHandlingClauseOptions
System.Reflection.ExceptionHandlingClause
System.Reflection.ReflectionTypeLoadException
System.Reflection.TargetException
System.Reflection.TargetInvocationException
System.Reflection.TargetParameterCountException
System.Reflection.Emit.ExceptionHandler
System.Runtime.Serialization.SerializationException
System.Runtime.ExceptionServices.HandleProcessCorruptedStateExceptionsAttribute
System.Runtime.ExceptionServices.FirstChanceExceptionEventArgs
System.Runtime.ExceptionServices.ExceptionDispatchInfo
System.Runtime.Remoting.RemotingException
System.Runtime.Remoting.ServerException
System.Runtime.Remoting.RemotingTimeoutException
System.Runtime.CompilerServices.RuntimeWrappedException
System.Runtime.InteropServices.COMException
System.Runtime.InteropServices.ExternalException
System.Runtime.InteropServices._Exception
System.Runtime.InteropServices.InvalidOleVariantTypeException
System.Runtime.InteropServices.MarshalDirectiveException
System.Runtime.InteropServices.SEHException
System.Runtime.InteropServices.InvalidComObjectException
System.Runtime.InteropServices.SafeArrayRankMismatchException
System.Runtime.InteropServices.SafeArrayTypeMismatchException
System.Text.DecoderExceptionFallback
System.Text.DecoderExceptionFallbackBuffer
System.Text.DecoderFallbackException
System.Text.EncoderExceptionFallback
System.Text.EncoderExceptionFallbackBuffer
System.Text.EncoderFallbackException
System.Windows.Forms.UnhandledExceptionMode
System.Windows.Forms.ThreadExceptionDialog
System.Windows.Forms.AxHost+InvalidActiveXStateException
System.UriFormatException
System.Configuration.ConfigurationException
System.Configuration.SettingsPropertyIsReadOnlyException
System.Configuration.SettingsPropertyNotFoundException
System.Configuration.SettingsPropertyWrongTypeException
System.Net.CookieException
System.Net.HttpListenerException
System.Net.ProtocolViolationException
System.Net.WebException
System.Net.WebExceptionStatus
System.Net.WebSockets.WebSocketException
System.Net.Mail.SmtpException
System.Net.Mail.SmtpFailedRecipientException
System.Net.Mail.SmtpFailedRecipientsException
System.Net.NetworkInformation.NetworkInformationException
System.Net.NetworkInformation.PingException
System.Net.Sockets.SocketException
System.Security.Authentication.AuthenticationException
System.Security.Authentication.InvalidCredentialException
System.Threading.BarrierPostPhaseException
System.Threading.ThreadExceptionEventArgs
System.Threading.ThreadExceptionEventHandler
System.IO.InvalidDataException
System.IO.InternalBufferOverflowException
System.ComponentModel.InvalidAsynchronousStateException
System.ComponentModel.InvalidEnumArgumentException
System.ComponentModel.LicenseException
System.ComponentModel.WarningException
System.ComponentModel.Win32Exception
System.ComponentModel.Design.CheckoutException
System.CodeDom.CodeThrowExceptionStatement
System.Text.RegularExpressions.RegexMatchTimeoutException
System.Drawing.Printing.InvalidPrinterException
System.Management.Automation.RuntimeException
System.Management.Automation.ScriptRequiresException
System.Management.Automation.RemoteException
System.Management.Automation.Runspaces.TypeTableLoadException
System.Management.Automation.ExtendedTypeSystemException
System.Management.Automation.MethodException
System.Management.Automation.MethodInvocationException
System.Management.Automation.GetValueException
System.Management.Automation.PropertyNotFoundException
System.Management.Automation.GetValueInvocationException
System.Management.Automation.SetValueException
System.Management.Automation.SetValueInvocationException
System.Management.Automation.PSInvalidCastException
System.Management.Automation.SettingValueExceptionEventArgs
System.Management.Automation.GettingValueExceptionEventArgs
Microsoft.PowerShell.Commands.HelpCategoryInvalidException
Microsoft.PowerShell.Commands.HelpNotFoundException
System.Management.Automation.Runspaces.InvalidRunspaceStateException
System.Management.Automation.Runspaces.RunspaceOpenModuleLoadException
System.Management.Automation.Runspaces.InvalidPipelineStateException
System.Management.Automation.InvalidPowerShellStateException
System.Management.Automation.Runspaces.InvalidRunspacePoolStateException
System.Management.Automation.InvalidJobStateException
System.Management.Automation.JobFailedException
System.Management.Automation.Remoting.PSRemotingDataStructureException
System.Management.Automation.Remoting.PSRemotingTransportException
System.Management.Automation.Remoting.PSRemotingTransportRedirectException
System.Management.Automation.Runspaces.RunspaceConfigurationAttributeException
System.Management.Automation.Runspaces.RunspaceConfigurationTypeException
System.Management.Automation.WildcardPatternException
System.Management.Automation.FlowControlException
System.Management.Automation.LoopFlowException
System.Management.Automation.BreakException
System.Management.Automation.ContinueException
System.Management.Automation.ExitException
System.Management.Automation.ScriptBlockToPowerShellNotSupportedException
System.Management.Automation.PSSecurityException
System.Management.Automation.Runspaces.PSConsoleLoadException
System.Management.Automation.Runspaces.PSSnapInException
System.Management.Automation.CommandNotFoundException
System.Management.Automation.ApplicationFailedException
System.Management.Automation.CmdletInvocationException
System.Management.Automation.CmdletProviderInvocationException
System.Management.Automation.PipelineStoppedException
System.Management.Automation.PipelineClosedException
System.Management.Automation.ActionPreferenceStopException
System.Management.Automation.ParentContainsErrorRecordException
System.Management.Automation.RedirectedException
System.Management.Automation.ScriptCallDepthException
System.Management.Automation.PipelineDepthException
System.Management.Automation.HaltCommandException
System.Management.Automation.Host.HostException
System.Management.Automation.Host.PromptingException
System.Management.Automation.MetadataException
System.Management.Automation.ValidationMetadataException
System.Management.Automation.ArgumentTransformationMetadataException
System.Management.Automation.ParsingMetadataException
System.Management.Automation.PSArgumentException
System.Management.Automation.PSArgumentNullException
System.Management.Automation.PSArgumentOutOfRangeException
System.Management.Automation.PSInvalidOperationException
System.Management.Automation.PSNotImplementedException
System.Management.Automation.PSNotSupportedException
System.Management.Automation.PSObjectDisposedException
System.Management.Automation.ParameterBindingException
System.Management.Automation.ParseException
System.Management.Automation.IncompleteParseException
System.Management.Automation.ProviderInvocationException
System.Management.Automation.SessionStateException
System.Management.Automation.SessionStateOverflowException
System.Management.Automation.SessionStateUnauthorizedAccessException
System.Management.Automation.ProviderNotFoundException
System.Management.Automation.ProviderNameAmbiguousException
System.Management.Automation.DriveNotFoundException
System.Management.Automation.ItemNotFoundException
System.Management.Automation.Runspaces.FormatTableLoadException
System.Management.Instrumentation.InstrumentationBaseException
System.Management.Instrumentation.InstrumentationException
System.Management.Instrumentation.InstanceNotFoundException
System.Diagnostics.Eventing.Reader.EventLogException
System.Diagnostics.Eventing.Reader.EventLogNotFoundException
System.Diagnostics.Eventing.Reader.EventLogReadingException
System.Diagnostics.Eventing.Reader.EventLogProviderDisabledException
System.Diagnostics.Eventing.Reader.EventLogInvalidDataException
System.ComponentModel.Composition.CompositionContractMismatchException
System.ComponentModel.Composition.ImportCardinalityMismatchException
System.ComponentModel.Composition.ChangeRejectedException
System.ComponentModel.Composition.CompositionException
System.ComponentModel.Composition.Primitives.ComposablePartException
System.Windows.ExceptionRoutedEventArgs
System.Windows.ResourceReferenceKeyNotFoundException
System.Windows.Data.UpdateSourceExceptionFilterCallback
System.Windows.Data.ValueUnavailableException
System.Windows.Markup.XamlParseException
System.Windows.Controls.ExceptionValidationRule
System.Windows.Controls.PrintDialogException
System.Security.RightsManagement.RightsManagementException
System.Windows.Threading.DispatcherUnhandledExceptionEventArgs
System.Windows.Threading.DispatcherUnhandledExceptionEventHandler
System.Windows.Threading.DispatcherUnhandledExceptionFilterEventArgs
System.Windows.Threading.DispatcherUnhandledExceptionFilterEventHandler
System.IO.FileFormatException
System.Windows.Media.InvalidWmpVersionException
System.Windows.Media.ExceptionEventArgs
System.Windows.Media.Animation.AnimationException
System.Xaml.XamlException
System.Xaml.XamlParseException
System.Xaml.XamlObjectWriterException
System.Xaml.XamlDuplicateMemberException
System.Xaml.XamlInternalException
System.Xaml.XamlSchemaException
System.Xaml.XamlObjectReaderException
System.Xaml.XamlXmlWriterException
System.Configuration.ConfigurationErrorsException
System.Configuration.Provider.ProviderException
System.Xml.XmlException
System.Xml.Schema.XmlSchemaException
System.Xml.Schema.XmlSchemaValidationException
System.Xml.Schema.XmlSchemaInferenceException
System.Xml.Xsl.XsltException
System.Xml.Xsl.XsltCompileException
System.Xml.XPath.XPathException
System.Runtime.Serialization.InvalidDataContractException
System.DirectoryServices.DirectoryServicesCOMException
System.DirectoryServices.ActiveDirectory.ActiveDirectoryObjectNotFoundException
System.DirectoryServices.ActiveDirectory.ActiveDirectoryOperationException
System.DirectoryServices.ActiveDirectory.ActiveDirectoryServerDownException
System.DirectoryServices.ActiveDirectory.ActiveDirectoryObjectExistsException
System.DirectoryServices.ActiveDirectory.SyncFromAllServersOperationException
System.DirectoryServices.ActiveDirectory.ForestTrustCollisionException
System.Management.ManagementException
Microsoft.Management.Infrastructure.CimException
System.Configuration.Install.InstallException
System.Transactions.TransactionException
System.Transactions.TransactionAbortedException
System.Transactions.TransactionInDoubtException
System.Transactions.TransactionManagerCommunicationException
System.Transactions.TransactionPromotionException
Microsoft.PowerShell.Commands.CertificateProviderItemNotFoundException
Microsoft.PowerShell.Commands.CertificateNotFoundException
Microsoft.PowerShell.Commands.CertificateStoreNotFoundException
Microsoft.PowerShell.Commands.CertificateStoreLocationNotFoundException
Microsoft.Management.UI.Internal.FilterExceptionEventArgs
System.Windows.Automation.ProxyAssemblyNotLoadedException
System.Windows.Automation.NoClickablePointException
System.Windows.Automation.ElementNotEnabledException
System.Windows.Automation.ElementNotAvailableException
Microsoft.SqlServer.Server.InvalidUdtException
System.Data.StrongTypingException
System.Data.TypedDataSetGeneratorException
System.Data.DataException
System.Data.ConstraintException
System.Data.DeletedRowInaccessibleException
System.Data.DuplicateNameException
System.Data.InRowChangingEventException
System.Data.InvalidConstraintException
System.Data.MissingPrimaryKeyException
System.Data.NoNullAllowedException
System.Data.ReadOnlyException
System.Data.RowNotInTableException
System.Data.VersionNotFoundException
System.Data.DBConcurrencyException
System.Data.InvalidExpressionException
System.Data.EvaluateException
System.Data.SyntaxErrorException
System.Data.OperationAbortedException
System.Data.SqlTypes.SqlTypeException
System.Data.SqlTypes.SqlNullValueException
System.Data.SqlTypes.SqlTruncateException
System.Data.SqlTypes.SqlNotFilledException
System.Data.SqlTypes.SqlAlreadyFilledException
System.Data.SqlClient.SqlException
System.Data.OleDb.OleDbException
System.Data.Odbc.OdbcException
System.Data.Common.DbException
Microsoft.PowerShell.Commands.WriteErrorException
Microsoft.PowerShell.Commands.StringManipulation.FlashExtractWrapper.FlashEx...
Microsoft.PowerShell.Commands.StringManipulation.FlashExtractWrapper.FlashEx...
Microsoft.PowerShell.Commands.StringManipulation.FlashExtractWrapper.Templat...
Microsoft.PowerShell.Commands.ProcessCommandException
Microsoft.PowerShell.Commands.ServiceCommandException
Microsoft.PowerShell.Commands.RestartComputerTimeoutException
Microsoft.PowerShell.Cmdletization.Cim.CimJobException
Microsoft.CSharp.RuntimeBinder.RuntimeBinderException
Microsoft.CSharp.RuntimeBinder.RuntimeBinderInternalCompilerException
System.ServiceProcess.TimeoutExceptionwhen exception occurs while executing external processes like .exe execution, ..., they can be handled using $LastExitCode powerShell variable.
when the launched process exits, powerShell will write the exit code directly to $LastExitCode
In most cases, exit code 0 means Success, and 1 means failure.
TODO Filter-Object
Where-Object
PS C:\> (1..15) | Where-Object { $_ -gt 10 }
11
12
13
14
15
PS C:\> (1..15).Where{ $_ -gt 10 } # Possible from version 4.0
11
12
13
14
15
TODO creating , reading and writing to files
To get all the profiles in the machine
PS C:\> Resolve-Path -Path C:\users\*\Desktop -ErrorAction SilentlyContinue
Path
----
C:\users\Administrator.JAINABHISHEK\Desktop
C:\users\JAINABHISHEK\Desktop
C:\users\Public\Desktop
To get only the names, and not the paths,
PS C:\> Resolve-Path -Path C:\users\*\Desktop -ErrorAction SilentlyContinue |
>> ForEach-Object {
>> $_.Path.Split('\')[-2]
>> }
>>
Administrator.JAINABHISHEK
JAINABHISHEK
Public
PS C:\> $User = [ordered]@{
FirstName = "jain"
LastName = "abhishek"
BirthDate = [DateTime]
UserName = "jainabhishek"
}
$data = Get-Input $User -Show
Write-Host $data
#System.Collections.Hashtable
PS C:\> $data
Name Value
---- -----
UserName jainabhishek
FirstName jain
LastName abhishek
BirthDate 6/16/2017 2:52:11 PM