Cut off text in string after/before separator in powershell

$pos = $name.IndexOf(";")
$leftPart = $name.Substring(0, $pos)
$rightPart = $name.Substring($pos+1)

Internally, PowerShell uses the String class.

$text = "test.txt ; 131 136 80 89 119 17 60 123 210 121 188 42 136 200 131 198"

$text.split(';')[1].split(' ')

You can use a Split :

$text = "test.txt ; 131 136 80 89 119 17 60 123 210 121 188 42 136 200 131 198"
$separator = ";" # you can put many separator like this "; : ,"

$parts = $text.split($separator)

echo $parts[0] # return test.txt
echo $parts[1] # return the part after the separator