Replacing strings in a file containing ${Some string in variable} in powershell -

i have text file contains keys of hash table in form of ${key}. need parse text file , replace ${key} it's value. below code using

    #$config hashtable    $document = get-content sample.txt     foreach ($conf in $config.keys) {         [string]$match = '${' + $conf + '}'         $document = $document.replace($match, $($config.$conf))         }     } 

i have tried below alternatives $match string

[string]$match = "`${" + $conf + "}"

[string]$match='${' $match+=$conf $match+='}' 

i tried hard coding string $match='${backup_folder}' in cases nothing. have tried -match see if matches returns false. have confirmed text file contains several patterns of ${key} format , if copy output of $match , search in file can find patterns. please point out what's wrong. using powershell v5.0

sample input

$config=@{"backup_dir"="_backup";"staging_dir"="_staging"} 

contents of sample.txt

overwrites contents of new installation old installation      use / path seperator-->     <!-- <rename path="" newname=""/> -->     <!--      ${backup_dir}     rename-> rename file/directory in new installation 

output: ${backup_dir} should replaced _backup

looks there're couple of typos in hashtable. following complete solution can save script , run, or copy console.

$document = @' overwrites contents of new installation old installation      use / path seperator-->     <!-- <rename path="" newname=""/> -->     <!--      ${backup_folder}     rename-> rename file/directory in new installation '@  $config=@{"backup_folder"="_backup";"staging_dir"="_staging"}  write-output "`n`ninput`n$document"  foreach ($conf in $config.keys) {         [string]$match = '${' + $conf + '}'         $document = $document.replace($match, $config.$conf) }  write-output "`n`noutput`n$document"