How to replace text in a string through powershell?-CodePudding

Suppose I have a file(local.tfvars) which consists of:

Car {  
}  
Bus {
}

Now I want to replace car in this file with

Car {
  Audi,
  Mercedes,
}  
Bus {
}

through the script.

I am fetching the local file through

 $localfile = Get-Content -Path ("local.tfvars")

after that I am using:

  $localfile.replace("Car","Car{`n Audi,Mercedes)

Which should give me the output as:

Car {
  Audi,  
  Mercedes,
}
Bus {
}

But the output doesn't seem to come in this way, the output that I am getting is:

Car {
  Audi,
}
Bus {  
}
Car {
  Mercedes,
}
Bus { 
}

See here these are getting printed twice which I don't want.

CodePudding user response：

Maybe this is what you're looking for?

$result = @'
{

Car {
}
Bus {
}

}
'@

$result = $result.Replace("Car {", "Car {`r`nAudi,`r`nMercedes,`r")

$result

CodePudding user response：

Although your example looks like JSON, it is not, so what you can do here is to read the file as single multiline string and use regex operator -replace on its content.

The easies way to retain the replacement's (multiline) format is by using a Here-String:

# replace with
$newCars = @'
Car {
  Audi,
  Mercedes,
} 
'@

# find the empty Cars node and replace it with above $newCars
# if you also want the output on screen, append switch `PassThru` to the Set-Content command
(Get-Content -Path "local.tfvars" -Raw) -replace '(?m)^Car\s*\{\s*}', $newCars | Set-Content -Path "local.tfvars"

Result:

Car {
  Audi,
  Mercedes,
}   
Bus {
}

Regex details:

(?m)       Match the remainder of the regex with the options: ^ and $ match at line breaks (m)
^          Assert position at the beginning of a line (at beginning of the string or after a line break character)
Car        Match the characters “Car” literally
\s         Match a single character that is a “whitespace character” (spaces, tabs, line breaks, etc.)
   *       Between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\{         Match the character “{” literally
\s         Match a single character that is a “whitespace character” (spaces, tabs, line breaks, etc.)
   *       Between zero and unlimited times, as many times as possible, giving back as needed (greedy)
}          Match the character “}” literally