powershell - What is the @ parameter? -

in powershell, few programs starts @' , ends '@, when type @' , press enter in powershell prompt throws error. can explain how can go this?

@'...'@ , @"..."@ "here strings" (documented in about_quoting_rules):

here-strings

the quotation rules here-strings different.

a here-string single-quoted or double-quoted string in quotation marks interpreted literally. here-string can span multiple lines. lines in here-string interpreted strings though not enclosed in quotation marks.

like regular strings, variables replaced values in double-quoted here-strings. in single-quoted here-strings, variables not replaced values.

you can use here-strings text, particularly useful following kinds of text:

-- text contains literal quotation marks -- multiple lines of text, such text in html or xml document -- text script or function 

a here-string can have either of following formats, represents linefeed or newline hidden character added when press enter key.

double-quotes:

   @"<enter>     <string> [string] ...<enter>     "@ 

single-quotes:

   @'<enter>     <string> [string] ...<enter>     '@ 

in either format, closing quotation mark must first character in line.

a here-string contains text between 2 hidden characters. in here-string, quotation marks interpreted literally. example:

   @"     help, type "get-help"     "@ 

the output of command is:

   help, type "get-help" 

using here-string can simplify using string in command. example:

   @"     use quotation mark (') begin string.     "@ 

the output of command is:

   use quotation mark (') begin string. 

in single-quoted here-strings, variables interpreted literally , reproduced exactly. example:

   @'     $profile variable contains path     of windows powershell profile.     '@ 

the output of command is:

   $profile variable contains path     of windows powershell profile. 

in double-quoted here-strings, variables replaced values. example:

   @"      if have not created profile,     path of profile file is:     $profile.     "@ 

the output of command is:

   if have not created profile,     path of profile file is:     c:\users\user01\documents\windowspowershell\microsoft.powershell_profile.ps1. 

here-strings typically used assign multiple lines variable. example, following here-string assigns page of xml $page variable.

   $page = [xml] @"     <command:command xmlns:maml="http://schemas.microsoft.com/maml/2004/10"     xmlns:command="http://schemas.microsoft.com/maml/dev/command/2004/10"      xmlns:dev="http://schemas.microsoft.com/maml/dev/2004/10">     <command:details>             <command:name>                    format-table             </command:name>             <maml:description>                 <maml:para>formats output table.</maml:para>             </maml:description>             <command:verb>format</command:verb>             <command:noun>table</command:noun>             <dev:version></dev:version>     </command:details>     ...     </command:command>     "@ 

here-strings convenient format input convertfrom-stringdata cmdlet, converts here-strings hash tables. more information, see convertfrom-stringdata.