This is the built-in help made by Microsoft for the command 'Start-Transaction', in PowerShell version 2 - as retrieved from
Windows version 'Microsoft® Windows Vista™ Ultimate ' PowerShell help files on 2016-06-23.
For PowerShell version 3 and up, where you have Update-Help, this command was run just before creating the web pages from the help files.
Starts a transaction.
Start-Transaction [-Independent] [-RollbackPreference {Error | TerminatingError | Never}] [-Timeout <int>] [-Confirm] [-WhatIf] [<CommonParameter
s>]
The Start-Transaction cmdlet starts a transaction, which is a series of commands that are managed as a unit. A transaction can be completed ("com
mitted"), or it can be completely undone ("rolled back") so that any data changed by the transaction is restored to its original state. Because t
he commands in a transaction are managed as a unit, either all commands are committed or all commands are rolled back.
By default, transactions are rolled back automatically if any command in the transaction generates an error, but you can use the RollbackPreferen
ce parameter to change this behavior.
The cmdlets used in a transaction must be designed to support transactions. Cmdlets that support transactions have a UseTransaction parameter. To
perform transactions in a provider, the provider must support transactions. The Windows PowerShell Registry provider in Windows Vista and later
versions of Windows supports transactions. You can also use the Microsoft.PowerShell.Commands.Management.TransactedString class to include expres
sions in transactions on any version of Windows that supports Windows PowerShell. Other Windows PowerShell providers can also support transaction
s.
Only one transaction can be active at a time. If you start a new, independent transaction while a transaction is in progress (neither completed n
or undone), the new transaction becomes the active transaction, and you must commit or roll back the new transaction before making any changes to
the original transaction.
The Start-Transaction cmdlet is one of a set of cmdlets that support the transactions feature in Windows PowerShell. For more information, see ab
out_Transactions.
<
Online version: http://go.microsoft.com/fwlink/?LinkID=135262
about_Transactions
Get-Transaction
Complete-Transaction
Undo-Transaction
Use-Transaction
<
-------------------------- EXAMPLE 1 --------------------------
C:\PS>cd hkcu:\software
PS HKCU:\software> start-transaction
PS HKCU:\software> new-item MyCompany -UseTransaction
PS HKCU:\software> new-itemproperty MyCompany -name MyKey -value 123 -UseTransaction
PS HKCU:\software> undo-transaction
Description
-----------
These commands start and then roll back a transaction. Because the transaction is rolled back, no changes are made to the registry.
-------------------------- EXAMPLE 2 --------------------------
C:\PS>cd hkcu:\software
PS HKCU:\software> start-transaction
PS HKCU:\software> new-item MyCompany -UseTransaction
PS HKCU:\software> new-itemproperty MyCompany -name MyKey -value 123 -UseTransaction
PS HKCU:\software> complete-transaction
Description
-----------
These commands start and then complete a transaction. No changes are made to the registry until the Complete-Transaction command is used.
-------------------------- EXAMPLE 3 --------------------------
C:\PS>cd HKCU:\software
PS HKCU:\software> start-transaction
PS HKCU:\software> new-item -path NoPath -name MyCompany -UseTransaction
PS HKCU:\software> new-item -path . -name MyCompany -UseTransaction
PS HKCU:\software> start-transaction -RollbackPreference never
PS HKCU:\software> new-item -path NoPath -name MyCompany -UseTransaction
PS HKCU:\software> new-item -path . -name MyCompany -UseTransaction
# Start-Transaction (-rollbackpreference error)
PS HKCU:\software> start-transaction
PS HKCU:\software> new-item -path NoPath -Name MyCompany -UseTransaction
New-Item : The registry key at the specified path does not exist.
At line:1 char:9
+ new-item <<<< -path NoPath -Name MyCompany -UseTransaction
PS HKCU:\software> new-item -path . -name MyCompany -UseTransaction
New-Item : Cannot use transaction. The transaction has been rolled back or has timed out.
At line:1 char:9
+ new-item <<<< -path . -name MyCompany -UseTransaction
# Start-Transaction (-rollbackpreference never)
PS HKCU:\software> start-transaction -RollbackPreference never
PS HKCU:\software> new-item -path NoPath -name MyCompany -UseTransaction
New-Item : The registry key at the specified path does not exist.
At line:1 char:9
+ new-item <<<< -path NoPath -name MyCompany -UseTransaction
PS HKCU:\software> new-item -path . -name MyCompany -UseTransaction
Hive: HKEY_CURRENT_USER\Software
SKC VC Name Property
--- -- ---- --------
0 0 MyCompany {}
PS HKCU:\Software> complete-transaction
# Succeeds
Description
-----------
This example demonstrates the effect of changing the RollbackPreference parameter value.
In the first set of commands, the Start-Transaction command does not use the RollbackPreference parameter. As a result, the default value ("Error
") is used. When an error occurs in a transaction command (the specified path does not exist), the transaction is automatically rolled back.
In the second set of commands, the Start-Transaction command uses the RollbackPreference parameter with a value of "Never". As a result, when an
error occurs in a transaction command, the transaction is still active and can be completed successfully.
Because most transactions must be performed without error, the default value of the RollbackPreference parameter is typically preferred.
-------------------------- EXAMPLE 4 --------------------------
C:\PS>cd HKCU:\software
PS HKCU:\software> start-transaction
PS HKCU:\software> new-item MyCompany -UseTransaction
PS HKCU:\software> start-transaction
PS HKCU:\software> get-transaction
PS HKCU:\software> new-item MyCompany2 -UseTransaction
PS HKCU:\software> complete-transaction
PS HKCU:\software> complete-transaction
PS HKCU:\Software> Get-Transaction
RollbackPreference SubscriberCount Status
------------------ --------------- ------
Error 2 Active
Description
-----------
This example shows the effect of using the Start-Transaction command while a transaction is in progress. The effect is much like joining the tran
saction in progress.
Although this is a simplified command, this scenario commonly occurs when the transaction involves running a script that includes a complete tran
saction.
The first Start-Transaction command starts the transaction. The first New-Item command is part of the transaction.
The second Start-Transaction command adds a new subscriber to the transaction. The Get-Transaction command now returns a transaction with a subsc
riber count of 2. The second New-Item command is part of the same transaction.
No changes are made to the registry until the entire transaction is completed. To complete the transaction, you must enter two Complete-Transacti
on commands, one for each subscriber. If you were to roll back the transaction at any point, the entire transaction would be rolled back for both
subscribers.
-------------------------- EXAMPLE 5 --------------------------
C:\PS>cd HKCU:\software
PS HKCU:\software> start-transaction
PS HKCU:\software> new-item MyCompany -UseTransaction
PS HKCU:\software> start-transaction -independent
PS HKCU:\software> get-transaction
PS HKCU:\software> undo-transaction
PS HKCU:\software> new-itemproperty -path MyCompany -name MyKey -value 123 -UseTransaction
PS HKCU:\software> complete-transaction
PS HKCU:\software> dir my*
PS HKCU:\Software> get-transaction
RollbackPreference SubscriberCount Status
------------------ --------------- ------
Error 1 Active
PS HKCU:\software> undo-transaction
PS HKCU:\software> new-itemproperty -path MyCompany -name MyKey -value 123 -UseTransaction
MyKey
-----
123
PS HKCU:\software> complete-transaction
PS HKCU:\software> dir my*
Hive: HKEY_CURRENT_USER\Software
SKC VC Name Property
--- -- ---- --------
0 1 MyCompany {MyKey}
Description
-----------
This example shows the effect of using the Independent parameter of Start-Transaction to start a transaction while another transaction is in prog
ress. In this case, the new transaction is rolled back without affecting the original transaction.
Although the transactions are logically independent, because only one transaction can be active at a time, you must roll back or commit the newes
t transaction before resuming work on the original transaction.
The first set of commands starts a transaction. The New-Item command is part of the first transaction.
In the second set of commands, the Start-Transaction command uses the Independent parameter. The Get-Transaction command that follows shows the t
ransaction object for the active transaction (the newest one). The subscriber count is equal to 1, showing that the transactions are unrelated.
When the active transaction is rolled back by using an Undo-Transaction command, the original transaction becomes active again.
The New-ItemProperty command, which is part of the original transaction, completes without error, and the original transaction can be completed b
y using the Complete-Transaction command. As a result, the registry is changed.
-------------------------- EXAMPLE 6 --------------------------
C:\PS>cd hkcu:\software
PS HKCU:\software> start-transaction
PS HKCU:\software> new-item MyCompany1 -UseTransaction
PS HKCU:\software> new-item MyCompany2
PS HKCU:\software> new-item MyCompany3 -UseTransaction
PS HKCU:\software> dir my*
PS HKCU:\software> complete-transaction
PS HKCU:\software> dir my*
PS HKCU:\Software> dir my*
Hive: HKEY_CURRENT_USER\Software
SKC VC Name Property
--- -- ---- --------
0 0 MyCompany2 {}
PS HKCU:\Software> complete-transaction
PS HKCU:\Software> dir my*
Hive: HKEY_CURRENT_USER\Software
SKC VC Name Property
--- -- ---- --------
0 0 MyCompany1 {}
0 0 MyCompany2 {}
0 0 MyCompany3 {}
Description
-----------
This example demonstrates that commands that are submitted while a transaction is in progress can be included in the transaction or not included.
Only commands that use the UseTransaction parameter are part of the transaction.
The first and third New-Item commands use the UseTransaction parameter. These commands are part of the transaction. Because the second New-Item c
ommand does not use the UseTransaction parameter, it is not part of the transaction.
The first "dir" command shows the effect. The second New-Item command is completed immediately, but the first and third New-Item commands are not
effective until the transaction is committed.
The Complete-Transaction command commits the transaction. As a result, the second "dir" command shows that all of the new items are added to the
registry.
-------------------------- EXAMPLE 7 --------------------------
C:\PS>start-transaction -timeout 2
# Wait two minutes...
C:\PS> get-transaction
C:\PS> new-item HKCU:\Software\MyCompany -UseTransaction
C:\PS> start-transaction -timeout 2
# Wait two minutes...
C:\PS>> get-transaction
RollbackPreference SubscriberCount Status
------------------ --------------- -----------
Error 1 RolledBack
C:\PS> new-item HKCU:\Software\MyCompany -UseTransaction
New-Item : Cannot use transaction. The transaction has been rolled back or has timed out.
At line:1 char:9
+ new-item <<<< MyCompany -UseTransaction
Description
-----------
This command uses the Timeout parameter of Start-Transaction to start a transaction that must be completed within two minutes. If the transaction
is not complete when the timeout expires, it is rolled back automatically.
When the timeout expires, you are not notified, but the Status property of the transaction object is set to RolledBack and commands that use the
UseTransaction parameter fail.