use variable on regex

Posted on 2016-07-28
Last Modified: 2016-07-29

I try to use variable $_.fg_name  on regex but the result is []

$file = "C:\test\mv_ddl.sql"
$_.fg_name = "Primary"

(Get-Content $file) | ForEach-Object {$_ -replace [regex]::Escape("ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]"), "ALLOW_PAGE_LOCKS  = ON) ON \[$($_.fg_name))\]" -replace [regex]::Escape(") ON [PRIMARY]"), ") ON \[$($_.fg_name))\] TEXTIMAGE_ON [LOB]"} | Set-Content $file

How can I resolve, please?


Question by:bibi92
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LVL 84

Expert Comment

ID: 41733343
$_ is the loop variable inside the ForEach, which is the string from the input file currently being processed.
Just use a regular variable (and please put code inside code style tags, see the buttons over the Edit field).
$file = "C:\test\mv_ddl.sql"
$fg_name = "Primary"

(Get-Content $file) | ForEach-Object {$_ -replace [regex]::Escape("ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]"), "ALLOW_PAGE_LOCKS  = ON) ON \[$($fg_name))\]" -replace [regex]::Escape(") ON [PRIMARY]"), ") ON \[$($fg_name))\] TEXTIMAGE_ON [LOB]"} | Set-Content $file

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LVL 12

Expert Comment

by:Dustin Saunders
ID: 41733350
You need to get that variable another way, $_ is referring to the object piped in.  For example:

1,2,3 | %{ write-host $_ } 

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So you need to reference the object which contains the property you want to use.  What object contains fg_name and can you post code where you are getting that object?

Author Comment

ID: 41733364
I test Obda solution the result for the variable is  \[)\].

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Author Comment

ID: 41733384
Thanks a lot
LVL 84

Accepted Solution

oBdA earned 500 total points
ID: 41733391
On closer inspection, you had a closing parenthesis too many, and since the patterns will be escaped by [regex]::Escape, you don't need to escape the square brackets.
$file = "C:\test\mv_ddl.sql"
$fg_name = "Primary"

(Get-Content $file) | ForEach-Object {$_ -replace [regex]::Escape("ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]"), "ALLOW_PAGE_LOCKS  = ON) ON [$($fg_name)]" -replace [regex]::Escape(") ON [PRIMARY]"), ") ON [$($fg_name)] TEXTIMAGE_ON [LOB]"} | Set-Content $file 

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Author Closing Comment

ID: 41734766

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