Supporting Wildcard Characters in Cmdlet Parameters
Often, you will have to design a cmdlet to run against a group of resources rather than against a single resource. For example, a cmdlet might need to locate all the files in a data store that have the same name or extension. You must provide support for wildcard characters when you design a cmdlet that will be run against a group of resources.
Using wildcard characters is sometimes referred to as globbing.
Windows PowerShell Cmdlets That Use Wildcards
Many Windows PowerShell cmdlets support wildcard characters for their parameter values. For
example, almost every cmdlet that has a
Path parameter supports wildcard characters for
these parameters. (Although most cmdlets that have a
Path parameter also have a
parameter that does not support wildcard characters.) The following command shows how a wildcard
character is used to return all the cmdlets in the current session whose name contains the Get
Supported Wildcard Characters
Windows PowerShell supports the following wildcard characters.
|Wildcard||Description||Example||Matches||Does not match|
|*||Matches zero or more characters, starting at the specified position||
||A, ag, Apple|
|?||Matches any character at the specified position||
||An, in, on||ran|
|[ ]||Matches a range of characters||
||book, cook, look||nook, took|
|[ ]||Matches the specified characters||
||book, nook||cook, look|
When you design cmdlets that support wildcard characters, allow for combinations of wildcard
characters. For example, the following command uses the
Get-ChildItem cmdlet to retrieve all the
.txt files that are in the c:\Techdocs folder and that begin with the letters "a" through "l."
The previous command uses the range wildcard
[a-l] to specify that the file name should begin
with the characters "a" through "l" and uses the
* wildcard character as a placeholder
for any characters between the first letter of the filename and the .txt extension.
The following example uses a range wildcard pattern that excludes the letter "d" but includes all the other letters from "a" through "f."
Handling Literal Characters in Wildcard Patterns
If the wildcard pattern you specify contains literal characters that should not be interpretted as
wildcard characters, use the backtick character (
`) as an escape character. When you specify
literal characters int the PowerShell API, use a single backtick. When you specify literal
characters at the PowerShell command prompt, use two backticks.
For example, the following pattern contains two brackets that must be taken literally.
When used in the PowerShell API use:
- "John Smith `[*`]"
When used from the PowerShell command prompt:
- "John Smith ``[*``]"
This pattern matches "John Smith [Marketing]" or "John Smith [Development]". For example:
PS> "John Smith [Marketing]" -like "John Smith ``[*``]" True PS> "John Smith [Development]" -like "John Smith ``[*``]" True
Cmdlet Output and Wildcard Characters
When cmdlet parameters support wildcard characters, the operation usually generates an array output.
Occasionally, it makes no sense to support an array output because the user might use only a single
item. For example, the
Set-Location cmdlet does not support array output because the user sets
only a single location. In this instance, the cmdlet still supports wildcard characters, but it
forces resolution to a single location.