We want to replace multiple instances of the variable `id=*`, with a certain pattern, like `id=1234`.
I already made this Powershell script (and prefer to keep using Powershell as solution):

```
$line = Get-Content C:\test.txt | Select-String "id=" | Select-Object -ExpandProperty Line
$content = Get-Content C:\test.txt
$content | ForEach {$_ -replace $line,"id=1234"} | Set-Content C:\test.txt
Get-Content C:\test.txt

```

This works, as long as there's only 1 instance of `id=...`, when a file contains multiple instances of `id=...` there is no replacement step performed at all.

The input file is similar to:

```
text over here
id=1
text over here: id={123456}
text
id=number1
id=#3 text 
id=3+3 text 

```

which should result in:

```
text over here
id=1234
text over here: id=1234
text
id=1234
id=1234 text 
id=1234 text 

```