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about_Regular_Expressions

Updated: May 20, 2009

Applies To: Windows PowerShell 2.0

TOPIC
    about_Regular_Expressions

SHORT DESCRIPTION
    Describes regular expressions in Windows PowerShell.
 

LONG DESCRIPTION
    Windows PowerShell supports the following regular expression characters.


        Format   Logic                            Example
        -------- -------------------------------  -----------------------
        value    Matches exact characters         "book" -match "oo"
                 anywhere in the original value.

        .        Matches any single character.    "copy" -match "c..y"

        [value]  Matches at least one of the      "big" -match "b[iou]g"
                 characters in the brackets.

        [range]  Matches at least one of the      "and" -match "[a-e]nd"
                 characters within the range.
                 The use of a hyphen (–) allows 
                 you to specify an adjacent 
                 character.

        [^]      Matches any characters except    "and" -match "[^brt]nd"
                 those in brackets.

        ^        Matches the beginning            "book" -match "^bo"
                 characters.

        $        Matches the end characters.      "book" -match "ok$"

        *        Matches any instances            "baggy" -match "g*"
                 of the preceding character.

        ?        Matches one instance             "baggy" -match "g?"
                 of the preceding character.

        \        Matches the character that       "Try$" -match "Try\$"
                 follows as an escaped character.


    Windows PowerShell supports the character classes available in 
    Microsoft .NET Framework regular expressions.


        Format   Logic                            Example
        -------- -------------------------------  -----------------------
        \p{name} Matches any character in the     "abcd defg" -match "\p{Ll}+"
                 named character class specified 
                 by {name}. Supported names are 
                 Unicode groups and block 
                 ranges such as Ll, Nd, 
                 Z, IsGreek, and IsBoxDrawing.
 
        \P{name} Matches text not included in     1234 -match "\P{Ll}+"
                 the groups and block ranges 
                 specified in {name}.
 
        \w       Matches any word character.      "abcd defg" -match "\w+"
                 Equivalent to the Unicode        (this matches abcd)
                 character categories [\p{Ll}
                 \p{Lu}\p{Lt}\p{Lo}\p{Nd}\p{Pc}]. 
                 If ECMAScript-compliant behavior 
                 is specified with the ECMAScript 
                 option, \w is equivalent to 
                 [a-zA-Z_0-9].
 
        \W       Matches any nonword character.   "abcd defg" -match "\W+"
                 Equivalent to the Unicode        (This matches the space)
                 categories [^\p{Ll}\p{Lu}\p{Lt}
                 \p{Lo}\p{Nd}\p{Pc}].
 
        \s       Matches any white-space          "abcd defg" -match "\s+"
                 character.  Equivalent to the 
                 Unicode character categories 
                 [\f\n\r\t\v\x85\p{Z}].
 
        \S       Matches any non-white-space      "abcd defg" -match "\S+"
                 character. Equivalent to the 
                 Unicode character categories 
                 [^\f\n\r\t\v\x85\p{Z}].
 
        \d       Matches any decimal digit.       12345 -match "\d+"
                 Equivalent to \p{Nd} for 
                 Unicode and [0-9] for non-
                 Unicode behavior.
 
        \D       Matches any nondigit.            "abcd" -match "\D+"
                 Equivalent  to \P{Nd} for 
                 Unicode and [^0-9] for non-
                 Unicode behavior.
 

    Windows PowerShell supports the quantifiers available in .NET Framework
    regular expressions. The following are some examples of quantifiers.


        Format   Logic                            Example
        -------- -------------------------------  -----------------------
        *        Specifies zero or more matches;  "abc" -match "\w*"
                 for example, \w* or (abc)*. 
                 Equivalent to {0,}.
  
        +        Matches repeating instances of   "xyxyxy" -match "xy+"
                 the preceding characters.

        ?        Specifies zero or one matches;   "abc" -match "\w?"
                 for example, \w? or (abc)?. 
                 Equivalent to {0,1}.
 
        {n}      Specifies exactly n matches;     "abc" -match "\w{2}"
                 for example, (pizza){2}. 
        
        {n,}     Specifies at least n matches;    "abc" -match "\w{2,}"
                 for example, (abc){2,}. 
        
        {n,m}    Specifies at least n, but no     "abc" -match "\w{2,3}"
                 more than m, matches. 


    All the comparisons shown in the preceding table evaluate to true.


    Notice that the escape character for regular expressions, a backslash (\),
    is different from the escape character for Windows PowerShell. The
    escape character for Windows PowerShell is the backtick character (`) 
    (ASCII 96).


    For more information, see the "Regular Expression Language Elements" topic
    in the Microsoft Developer Network (MSDN) library 
    at http://go.microsoft.com/fwlink/?LinkId=133231. 


SEE ALSO    
    about_Comparison_Operators
    about_Operators   



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