Use list of files saved in text file to search for string in powershell

Question

I have 2 sets of operations, in the 1st one I look for files that contain a string, then in second one I use that list to extract lines that contains another string and then edit them.

$List_Of_Files = Get-ChildItem "$outputfolder*.html" -recurse | 
  Select-String -pattern "https://www.youtube.com" | group path | 
    select name -ExpandProperty Name

$List_Of_Titles = @(Get-Content $List_Of_Files | Where-Object { $_.Contains("<title>") }) | 
  Foreach-Object {
    $content = $_ -replace "    <title>", "  <video:title>";
    $content -replace "</title>", "</video:title>"
  }

Code works as expected, but the problem is that I need the 1st set of operations to output results into a text file and then use that file in second set which should also output results into another text file.

I have tried the following, but second set doesn't create the file, but doesn't give me any error either.

Get-ChildItem "$outputfolder*.html" -recurse | 
  Select-String -pattern "https://www.youtube.com" | group path | 
    select name -ExpandProperty Name | Set-Content "c:\List_Of_Files.txt"

@(Get-Content "c:\List_Of_Files.txt" | Where-Object { $_.Contains("<title>") }) |
 Foreach-Object {
    $content = $_ -replace "    <title>", "  <video:title>";
    $content -replace "</title>", "</video:title>"
 } | Set-Content "c:\list_of_titles.txt"

I have tried to modify it in different ways, but can't figure out how to make it work.

I just tested it with a dummy file containing some <title> tags and your last pipeline worked. Could you show as a digest of the content of List_Of_Files.txt? — DAXaholic
– DAXaholic, Commented Jun 24, 2016 at 16:19
Side note: Set-Content produces ASCII files by default, causing any foreign chars. to be replaced with literal ? chars.; if that's a problem, use the -Encoding parameter to change that. — mklement0
– mklement0, Commented Jun 24, 2016 at 16:24
List_Of_Files.txt just contain complete path to files for example: c:\folder\another folder\some file name that contains a string.html etc. etc — Peter Pavelka
– Peter Pavelka, Commented Jun 24, 2016 at 16:28

mklement0 · Accepted Answer · 2016-06-24 19:18:10Z

1

c:\List_Of_Files.txt contains a list of file paths and you're trying to filter that list by whether the path contains "<title>", which results in no matches.
(I have no explanation for why your 1st snippet worked.)

Your problem stems from confusion over what objects are being passed through the pipeline: you start with file paths (strings), then threat them as if they were the files' content.

Instead, I assume you meant to test the contents of each file identified by its path.

A quick fix would be:

Get-Content "c:\List_Of_Files.txt" | Where-Object { Select-String -Quiet '<title>' $_ }

Note, however, that you must also adapt the ForEach-Object command accordingly:

Foreach-Object {
    # Read the content of the file whose path was given in $_,
    # and modify it.
    # (If you don't want to save the modifications, omit the `Set-Content` call.)
    $content = ((Get-Content $_) -replace "    <title>", "  <video:title>");       
    $content = $content -replace "</title>", "</video:title>";
    # Save modifications back to the input file (if desired).
    Set-Content -Value $content -Path $_;
    # $content is the entire document, so to output only the title line(s) 
    # we need to match again:
    $content -match '<video:title>'
    # Note: This relies on the title HTML element to be on a *single* line
    #       *of its own*, which may not be the case; 
    #       if it isn't, you must use proper HTML parsing to extract it.
 }

To put it all together:

Get-Content "c:\List_Of_Files.txt" | Where-Object { Select-String -Quiet '<title>' $_ } | 
    Foreach-Object {
        $content = ((Get-Content $_) -replace "    <title>", "  <video:title>");
        $content = $content -replace "</title>", "</video:title>";
        Set-Content -Value $content -Path $_;
        $content -match '<video:title>'
     } | Set-Content "c:\list_of_titles.txt"

Note that you can make the whole command more efficient by removing the filtering step that uses Select-String and performing the filtering inside the ForEach-Object block.

Also, the string replacement could be optimized or, preferably, handled with true HTML parsing.

edited Jun 24, 2016 at 19:18

answered Jun 24, 2016 at 17:04

mklement0

452k68 gold badges728 silver badges988 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Peter Pavelka Over a year ago

Thanks, i don't know how to "finish" your code, in the last line of the ForEach-Object block i have put path to a text file like this - $_ c:\list_of_titles.txt but i get error saying - Unexpected token 'c:\list_of_titles.txt' in expression or statement. Could you let me know how to fix it please? Sorry for the confusion i obviously don't know much about powershell.

mklement0 Over a year ago

@PeterPavelka: It sounds like you were converting my code back to a one-liner and simply forgot a ; before $_ (in multiline code you don't need a ; at the end of a line). The more important question, however: what are you trying to save to "c:\list_of_titles.txt"? Is it the file paths or the actual title strings? If the latter, the code won't work.

Peter Pavelka Over a year ago

No i didn't do anything else except adding "c:\list_of_titles.txt" at the end as you suggested, and i need to save the actual titles as i explained in the original question, 1st snippet gives me list of files that include a string https://www.youtube.com , then i use that list in 2nd snipped to extract lines with string "</title>" and then in all those lines i replace title tags by video title tags and save the results into a file, so yes i need the actual titles as output.

mklement0 Over a year ago

@PeterPavelka: Please see my update (just revised), and note the caveat re HTML parsing.

Collectives™ on Stack Overflow

Use list of files saved in text file to search for string in powershell

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related