Trouble with Regular Expression matching in PowerShell when lines contain "$" sign

I am trying to perform search and replace using RegExs in PowerShell like the following:

Julie found "NoMoney" in "Easter Island" => Julie("Easter Island") = "NoMoney"

John found $SomeMoney$ in "Greenland" => John("Greenland") = $SomeMoney$

Jimmy found $$LotsOfMoney in "Treasure Island" => Jimmy("Treasure Island") = $$LotsOfMoney

Judy found $5 in Tribeca.NY => Judy(Tribeca.NY) = $5

Because the "$" sign has a special meaning in PowerShell REs I am unable to do this successfully for all but the first test where there is no "$". I have tried to escape the $ with backslashes, backticks, and tried combining both as well but no luck.

Can someone help?

Solution

Because the "$" sign has a special meaning in PowerShell REs I am unable to do this successfully for all but the first test where there is no "$". I have tried to escape the $ with backslashes, backticks, and tried combining both as well but no luck.

You don't need to match a literal $ to describe the listed strings at all:

$pattern = '^(?<who>\p{Lu}[\w\s]+?) found (?<what>.+?) in (?<where>.+)$'

$testStrings = @(
  'Julie found "NoMoney" in "Easter Island"'
  'John found $SomeMoney$ in "Greenland"'
  'Jimmy found $$LotsOfMoney in "Treasure Island"'
  'Judy found $5 in Tribeca.NY'
)

$testStrings |ForEach-Object {
  if ($_ -match $pattern) {
    "${_} => {0}({1}) = {2}" -f $Matches['who','where','what']
  }
}

Outputs:

Julie found "NoMoney" in "Easter Island" => Julie("Easter Island") = "NoMoney"
John found $SomeMoney$ in "Greenland" => John("Greenland") = $SomeMoney$
Jimmy found $$LotsOfMoney in "Treasure Island" => Jimmy("Treasure Island") = $$LotsOfMoney
Judy found $5 in Tribeca.NY => Judy(Tribeca.NY) = $5

The pattern used above describes:

^                   # start of string
(                   
  ?<who>            
  \p{Lu}            # 1 upper-case letter
  [\w\s]+?          # lazily followed by 1 or more word- or whitespace characters 
)                   
 found              # literal substring " found "
(                   
  ?<what>           
  .+?               # lazily followed by at least 1 of any character
)                   
 in                 # literal substring " in "
(                   
  ?<where>          
  .+                # followed by at least 1 of any character
)                   
$                   # end of string

All the grouping constructs of the form (?<label>pattern) are named capture groups, allowing us to attach labels to matched/captured substrings.

The $Matches variable used to store the capture group values is PowerShell-specific, see about_Regular_Expressions for more information

Although this question appears to arise from an XY problem, for completeness here is the correct escape sequence for a literal $ in a .NET regex pattern:

\$

You can also produce this subpattern programmatically with [regex]::Escape:

PS ~> [regex]::Escape('$')
\$