How do I do a conditional replace in PowerShell? - powershell

Question

Powershell Newbie looking for some help.
I've got a powershell script which changes a priority value inside a text file to have a value of 50:
if ($line.contains("Priority") )
{
$LastComma = $line.LastIndexOf(",") +1
$N = $line.Substring(0,$LastComma)
$N = $N + "50"
$lines[$counter] = $N
}
This works fine and does exactly what I want it to, but I now need to modify it so it changes the priority value to 45 if there is also the following line present:
Provider = XYZ
If this Provider value is not XYZ then all Priority values are set to 50 as before. Anyone have any advice on how can I achieve this?
Thanks

Answer 1

This example illustrates using Powershell with several concepts:
Matching each line using regular expressions
Replacing each line using regular expressions
Using a switch statement
Here's a test file:
Set-Content test.txt "Provider=ABC,Priority=3
Provider=DEF,Priority=4
Not a provider
Provider=XYZ,Priority=5"
You can transform the test file line by line using the
switch statement (thanks #TheIncorrigible1)
switch -Regex -File test.txt
{
'Provider=XYZ.+Priority='
{
$_ -replace "Priority=\d+","Priority=45"
continue
}
'Priority='
{
$_ -replace "Priority=\d+","Priority=50"
continue
}
default
{
$_
continue
}
}

Answer 2

Please make the effort to provide a working example next time.
Without any more information than what was provided, here is a draft of a solution:
foreach ($line in $lines) {
$value = "XYZ"
$check = $false
if ($line.contains("Provider = $value")) {
$check = $true
}
if ($line.contains("Priority")) {
if ($check) {
$priority = 45
} else {
$priority = 50
}
$LastComma = $line.LastIndexOf(",") +1
$N = $line.Substring(0,$LastComma)
$N = $N + "$priority"
$lines[$counter] = $N
}
}
Remark: This assume that the Provider tag will be found prior to the Priority tags.