powershell: remove text from end of string

Question

--deleted earlier text - I asked the wrong question!

ahem....

What I have is $var = "\\unknowntext1\alwaysSame\unknowntext2"

I need to keep only "\\unknowntext1"

Answer 1

Try regular expressions:

$foo = 'something_of_unknown' -replace 'something.*','something'

Or if you know only partially the 'something', then e.g.

'something_of_unknown' -replace '(some[^_]*).*','$1'
'some_of_unknown' -replace '(some[^_]*).*','$1'
'somewhatever_of_unknown' -replace '(some[^_]*).*','$1'

The $1 is reference to group in parenthesis (the (some[^_]*) part).

Edit (after changed question):

If you use regex, then special characters need to be escaped:

"\\unknowntext1\alwaysSame\unknowntext2" -replace '\\\\unknowntext1.*', '\\unknowntext1'

or (another regex magic) use lookbehind like this:

"\\unknowntext1\alwaysSame\unknowntext2" -replace '(?<=\\\\unknowntext1).*', ''

(which is: take anything (.*), but there must be \\unknowntext1 before it ('(?<=\\\\unknowntext1)) and replace it with empty string.

Edit (last)

If you know that there is something known in the middle (the alwaysSame), this might help:

"\\unknowntext1\alwaysSame\unknowntext2" -replace '(.*?)\\alwaysSame.*', '$1'

Answer 2

What I have is $var = "\unknowntext1\alwaysSame\unknowntext2"

I need to keep only "\unknowntext1"

Not sure this requires a regular expression. Assuming alwaysSame is literally always the same, as the discussion around stej's answer suggests, it seems by far the most straightforward way to accomplish this would be:

$var.substring(0, $var.indexOf("\alwaysSame"));

Answer 3

function Remove-TextAfter {   
    param (
        [Parameter(Mandatory=$true)]
        $string, 
        [Parameter(Mandatory=$true)]
        $value,
        [Switch]$Insensitive
    )

    $comparison = [System.StringComparison]"Ordinal"
    if($Insensitive) {
        $comparison = [System.StringComparison]"OrdinalIgnoreCase"
    }

    $position = $string.IndexOf($value, $comparison)

    if($position -ge 0) {
        $string.Substring(0, $position + $value.Length)
    }
}

Remove-TextAfter "something_of_unknown" "SoMeThInG" -Insensitive