Describes the keywords in the Windows PowerShell scripting language. (about_Language_Keywords)
TOPICabout_Language_KeywordsSHORT DESCRIPTIONDescribes the keywords in the Windows PowerShell scripting language.LONG DESCRIPTIONWindows PowerShell has the following language keywords. For more information, see the about topic for the keyword and the information that follows the table. Keyword Reference ------- --------- Begin about_Functions, about_Functions_Advanced Break about_Break, about_Trap Catch about_Try_Catch_Finally Continue about_Continue, about_Trap Data about_Data_Sections Do about_Do, about_While Dynamicparam about_Functions_Advanced_Parameters Else about_If Elseif about_If End about_Functions, about_Functions_Advanced_Methods Exit Described in this topic. Filter about_Functions Finally about_Try_Catch_Finally For about_For Foreach about_Foreach From Reserved for future use. Function about_Functions, about_Functions_Advanced If about_If In about_Foreach Param about_Functions Process about_Functions, about_Functions_Advanced Return about_Return Switch about_Switch Throw about_Throw, about_Functions_Advanced_Methods Trap about_Trap, about_Break, about_Try_Catch_Finally Try about_Try_Catch_Finally Until about_Do While about_While, about_Do Language Keywords Begin ----- Specifies one part of the body of a function, along with the Dynamicparam, Process, and End keywords. The Begin statement list runs one time before any objects are received from the pipeline. Syntax: function <name> { dynamicparam {<statement list>} begin {<statement list>} process {<statement list>} end {<statement list>} } Break ----- Causes a script to exit a loop. Syntax: while (<condition>) { <statements> ... break ... <statements> } Catch ----- Specifies a statement list to run if an error occurs in the accompanying Try statement list. An error type requires brackets. The second pair of brackets indicates that the error type is optional. Syntax: try {<statement list>} catch [[<error type>]] {<statement list>} Continue -------- Causes a script to stop running a loop and to go back to the condition. If the condition is met, the script begins the loop again. Syntax: while (<condition>) { <statements> ... continue ... <statements> } Data ---- In a script, defines a section that isolates data from the script logic. Can also include If statements and some limited commands. Syntax: data <variable> [-supportedCommand <cmdlet-name>] {<permitted content>} Do -- Used with the While or Until keyword as a looping construct. Windows PowerShell runs the statement list at least one time, unlike a loop that uses While. Syntax: do {<statement list>} while (<condition>) do {<statement list>} until (<condition>) Dynamicparam ------------ Specifies one part of the body of a function, along with the Begin, Process, and End keywords. Dynamic parameters are added at run time. Syntax: function <name> { dynamicparam {<statement list>} begin {<statement list>} process {<statement list>} end {<statement list>} } Else ---- Used with the If keyword to specify the default statement list. Syntax: if (<condition>) {<statement list>} else {<statement list>} Elseif ------ Used with the If and Else keywords to specify additional conditionals. The Else keyword is optional. Syntax: if (<condition>) {<statement list>} elseif (<condition>) {<statement list>} else {<statement list>} End --- Specifies one part of the body of a function, along with the Dynamicparam, Begin, and End keywords. The End statement list runs one time after all the objects have been received from the pipeline. Syntax: function <name> { dynamicparam {<statement list>} begin {<statement list>} process {<statement list>} end {<statement list>} } Exit ---- Causes Windows PowerShell to exit a script or a Windows PowerShell instance. Syntax: exit Filter ------ Specifies a function in which the statement list runs one time for each input object. It has the same effect as a function that contains only a Process block. Syntax: filter <name> {<statement list>} Finally ------- Defines a statement list that runs after statements that are associated with Try and Catch. A Finally statement list runs even if you press CTRL+C to leave a script or if you use the Exit keyword in the script. Syntax: try {<statement list>} catch [<error type] {<statement list>} finally {<statement list>} For --- Defines a loop by using a condition. Syntax: for (<initialize>; <condition>; <iterate>) {<statement list>} Foreach ------- Defines a loop by using each member of a collection. Syntax: foreach (<item> in <collection>){<statement list>} From ----- Reserved for future use. Function -------- Creates a named statement list of reusable code. You can name the scope a function belongs to. And, you can specify one or more named parameters by using the Param keyword. Within the function statement list, you can include Dynamicparam, Begin, Process, and End statement lists. Syntax: function [<scope:>]<name> { param ([type]<$pname1> [, [type]<$pname2>]) dynamicparam {<statement list>} begin {<statement list>} process {<statement list>} end {<statement list>} } You also have the option of defining one or more parameters outside the statement list after the function name. Syntax: function [<scope:>]<name> [([type]<$pname1>, [[type]<$pname2>])] { dynamicparam {<statement list>} begin {<statement list>} process {<statement list>} end {<statement list>} } If -- Defines a conditional. Syntax: if (<condition>) {<statement list>} In -- Used in a Foreach statement to create a loop that uses each member of a collection. Syntax: foreach (<item> in <collection>){<statement list>} Param ----- Defines the parameters in a function. Syntax: function [<scope:>]<name> { param ([type]<$pname1>[, [[type]<$pname2>]]) <statement list> } Process ------- Specifies a part of the body of a function, along with the Dynamicparam, Begin, and End keywords. When a Process statement list receives input from the pipeline, the Process statement list runs one time for each element from the pipeline. If the pipeline provides no objects, the Process statement list does not run. If the command is the first command in the pipeline, the Process statement list runs one time. Syntax: function <name> { dynamicparam {<statement list>} begin {<statement list>} process {<statement list>} end {<statement list>} } Return ------ Causes Windows PowerShell to leave the current scope, such as a script or function, and writes the optional expression to the output. Syntax: return [<expression>] Switch ------ Specifies a variety of actions to be performed on items from the pipeline or from a file. You can use either of the following syntax models. Syntax 1: switch [-regex|-wildcard|-exact][-casesensitive] ( pipeline ) { <string>|<number>|<variable>|{ <expression> } {<statement list>} <string>|<number>|<variable>|{ <expression> } {<statement list>} ... default {<statement list>} } Syntax 2: switch [-regex|-wildcard|-exact][-casesensitive] -file filename { <string>|<number>|<variable>|{ <expression> } {<statement list>} <string>|<number>|<variable>|{ <expression> } {<statement list>} ... default {<statement list>} } Throw ----- Throws an object as an error. Syntax: throw [<object>] Trap ---- Defines a statement list to be run if an error is encountered. An error type requires brackets. The second pair of brackets indicates that the error type is optional. Syntax: trap [[<error type>]] {<statement list>} Try --- Defines a statement list to be checked for errors while the statements run. If an error occurs, Windows PowerShell continues running in a Catch or Finally statement. An error type requires brackets. The second pair of brackets indicates that the error type is optional. Syntax: try {<statement list>} catch [[<error type]] {<statement list>} finally {<statement list>} Until ----- Used in a Do statement as a looping construct where the statement list is executed at least one time. Syntax: do {<statement list>} until (<condition>) While ----- Used in a Do statement as a looping construct where the statement list is executed at least one time. Syntax: do {<statement list>} while (<condition>) SEE ALSO about_escape_characters about_special_characters about_wildcards C:\Windows>powershell get-help about_Line_Editing -full
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