Replacing multiple lines in a file - windows

Question

I try to make, the line from the first array is read from a file and is replaced with a line from the second array, so some times with different lines. I made a script, but I do not understand why it does not work.
$OldStrings = #(
"desktopwidth:i:1440",
"desktopheight:i:900",
"winposstr:s:0,1,140,60,1596,999"
)
$NewStrings = #(
"desktopwidth:i:1734",
"desktopheight:i:990",
"winposstr:s:0,1,50,7,1800,1036"
)
$LinesArray = Get-Content -Path 'C:\temp\My Copy\Default.rdp'
$LinesCount = $LinesArray.Count
for ($i=0; $i -lt $LinesCount; $i++) {
foreach ($OldString in $OldStrings) {
foreach ($NewString in $NewStrings) {
if ($LinesArray[$i] -like $OldString) {
$LinesArray[$i] = $LinesArray[$i] -replace $OldString, $NewString
Write-Host "`nline" $i "takes on value:" $LinesArray[$i] "`n" -ForegroundColor Gray
}
}
}
}
The file is probably why it is not read at all.
After executing the script, I see only
line 2 takes on value: desktopwidth:i:1734
line 3 takes on value: desktopwidth:i:1734
line 5 takes on value: desktopwidth:i:1734

Answer 1

You're looking through the string arrays twice. You want to do two loops, one for each line in the file AND another for each count in the lines you're replacing. I think this should work:
$OldStrings = #(
"desktopwidth:i:1440",
"desktopheight:i:900",
"winposstr:s:0,1,140,60,1596,999"
)
$NewStrings = #(
"desktopwidth:i:1734",
"desktopheight:i:990",
"winposstr:s:0,1,50,7,1800,1036"
)
$LinesArray = Get-Content -Path 'C:\temp\My Copy\Default.rdp'
# loop through each line
for ($i=0; $i -lt $LinesArray.Count; $i++)
{
for ($j=0;$j -lt $OldStrings.Count; $j++)
{
if ($LinesArray[$i] -match $OldStrings[$j])
{
$LinesArray[$i] = $LinesArray[$i] -replace $OldStrings[$j],$NewStrings[$j]
Write-Host "`nline" $i "takes on value:" $LinesArray[$i] "`n" -ForegroundColor Gray
}
}
}
$LinesArray | Set-Content -Path 'C:\temp\My Copy\Default.rdp'

Answer 2

You don't need to bother checking the lines to look for matches. Since you have the replacements ready just do the replacements outright anyway. Should be faster this way as well.
$stringReplacements = #{
"desktopwidth:i:1440" = "desktopwidth:i:1734"
"desktopheight:i:900" = "desktopheight:i:990"
"winposstr:s:0,1,140,60,1596,999" = "winposstr:s:0,1,50,7,1800,1036"
}
$path = 'C:\temp\My Copy\Default.rdp'
# Read the file in as a single string.
$fileContent = Get-Content $path | Out-String
# Iterate over each key value pair
$stringReplacements.Keys | ForEach-Object{
# Attempt the replacement for each key/pair search/replace pair
$fileContent =$fileContent.Replace($_,$stringReplacements[$_])
}
# Write changes back to file.
# $fileContent | Set-Content $path
$stringReplacements is a key value hash of search and replace strings. I don't see you writing the changes back to file so I left a line on the end for you to uncomment.
You could add in checks to do the replacements still if you value the write-host lines but I figured that was for debugging and you already know how to do that.