Hi, I am using Select-String to find the line in a file that matches a string. I know the file will always be in the first few lines, so I only want to get the first match then stop the search, because the file is huge. I have retrieved the line, but what is the best way to delete the line from the file?

See attachment for input file and code.

This is what I can think of now:

$testXML = [System.Collections.ArrayList] (gc .\testxml.xml)
$testXML.Remove("String to be removed") # This will remove the first instance of the string in the list array.
Out-File -FilePath updatedtestxml.xml -InputObject $testXML $Encoding default

Unfortunately, if you want to replace a specific line of text in a text file, you have to re-write the entire file once you've found the line you want to replace.

I don't know how long your XML file is because the attachment got messed up, however, I recently had a scenario where I had to see if a string existed in a 250,000 line XML file, and add it if it wasn't there, and I had to compare each line with 10 different strings. However, doing that literally took maybe half a second, so I wouldn't worry about performance too much if you aren't going to be doing this frequently.

If you're still curious as to what the best way is, the best way would be to create a new file to write to as you are reading from the original file. That way, you aren't putting the entire file in memory all at once. Another thing to consider is that when re-writing the original text file, you are in danger of data loss if the re-writing operation fails half-way through, and that's why using a proxy text file is an advantage in this case.

Thank you sureshbabutadisetty, your suggestion worked perfectly and effeciently. Thanks GWHowarth88, good advice to write to a new file to avoid errors.

I had a bit of trouble converting my Select-String output to a string, but got there in the end:

$myLine = Select-String -Path $file -Pattern "string to be matched" -List | Select-Object Line
$myString = $myLine.Line

There is a more efficient way to do this for anyone interested. See this post:

http://stackoverflow.com/questions/...wer/submit

Essentially, cast to [xml] created 2 items: string (probably from the DTD part) and xml. In order to parse the XML, you need to access it like so:

[xml]$xml = (get-content "file.xml")
# to access the root node of the xml:
$xml.root[1]