change line in text file

Can someone help me on changing a whole line in a text file? For example if I have a line that says "site status: 0" on line 1. I want to change the whole line to say "site status: 1"

Ok here is my first powershell script written by me by scratch.

$count=0
$Status=(get-content c:\sitestatus.txt )
clear-content c:\sitestatus.txt
foreach ($i in $Status) {
$count++
if ($count -eq 1) {
$out=$i -replace "site status: 0", "site status: 1"
}
else
{
$out=$i
}
$out | add-content  c:\sitestatus.txt
}

I am sure it can be refined and I am also sure it can be done better but this is the best I can muster at this stage in my learning.

I like it. If I understand the OP though the number of the line is unknown. So I think I would do it like this:

$out = @()
foreach ($line in $(Get-Content c:\status.txt)){
  if ($line -eq 'site status: 0'){
    $line = 'site status: 1'
  }
  $out += $line
}
$out | Out-File -FilePath c:\status.txt

Thanks Ebgreen, I will study this, looks like outfile might be better than add-content in this case and I will have to work out what @() does

Yes my version only replaces line1 of the file

@() creates an empty array. Out-File or Add-Content either one work. The difference is one writes one time and the other has to write for every line.

Ah, thanks, I get it now. I did read that, you saved me flipping through my book :)

I came back to this question for nostalgic reasons. (It being my first PowerShell script and all)
This how I would do it now utilising the pipeline.
 
$log = "C:\status.txt"
(Get-Content $log) | foreach{$_.replace("site status: 0","site status: 1")} | Set-Content $log
Invoke-Item $log
 
The thing about PowerShell that really trumps vbscript is that you can knock out a simple script like this from the top of your head and not have to refer to your little code repository of snipits to read write files etc. Also what I have written there is long hand. This is truly a one liner...
 
(GC "C:\status.txt") | %{$_.replace("site status: 0","site status: 1")} | SC "C:\status.txt"
 
Notice how the get-content bit is in brackets? That is so the process of reading the file is complete before moving on. Now we can save to the same file we are reading from. Also notice how you can bash it out using alias names.