How to recursively search all files in a directory and sub-directories using PowerShell? - linux

Question

I'm not understanding where the recursion is occurring nor how it's used in the below tree function (which is meant to emulate some of the linux tree command results).
From the tree function, how are files (or file names and their path) passed to, here, a SearchString function?
for context, here's a REPL session demonstrating the end-goal on a single file: getting the PSPath property for a file, and using that property for a simple regex.
Session transcript:
posh> $dir = "/home/nicholas/Calibre Library/Microsoft Office User/549 (1476)"
posh> $files = Get-ChildItem -Path $dir –File
posh> $files.Length
3
posh> $files[0].Extension
.txt
posh> $files[0].PSPath
Microsoft.PowerShell.Core\FileSystem::/home/nicholas/Calibre Library/Microsoft Office User/549 (1476)/549 - Microsoft Office User.txt
posh> $pattern = '(?=.*?foo)(?=.*?bar)'
posh> $string = Get-Content $files[0]
posh> $string | Select-String $pattern
This file doesn't have any "foo" and "bar" matches. The goal is to search the entire Calibre library using PowerShell as above.
large output from a tree of the Calibre library trimmed to a single result:
Directory: /home/nicholas/Calibre Library/Microsoft Office User/548 (1474)
Mode LastWriteTime Length Name
---- ------------- ------ ----
----- 2/20/2021 3:22 AM 159883 548 - Microsoft Office User.txt
----- 2/20/2021 2:13 AM 351719 cover.jpg
----- 2/20/2021 2:39 AM 1126 metadata.opf
posh> ./worker.ps1
How is the above file and path passed to the SearchString function?
the goal being to iterate through the entire library and search all plain-text file. (Assumption being that plain-text files have a ".txt" extension.)
library code:
function SearchFile($dir,$file)
{
$path = [string]::Concat($dir,"/",$file)
$pattern='(?=.*?foo)(?=.*?bar)'
$string = Get-Content $path
$result = $string | Select-String $pattern
$result
}
function tree($dir)
{
"$dir"
$tree = Get-ChildItem -Recurse
$tree = Get-ChildItem -Path $dir -Recurse
# get any files and invoke SearchFile here ?
$tree
}
worker code:
. /home/nicholas/powershell/functions/library.ps1
$dir = "/home/nicholas/Calibre Library"
tree $dir
The execution of the SearchFile function should be triggered when a ".txt" file is found. That logic is missing. But the larger missing piece is how to invoke SearchFile from the tree function so that every file gets searched.
How is that done? Leaving aside the file-type or file extension. Not seeing where the recursion occurs.

Answer 1

You are really overcomplicating things. You can do this very easily by using Get-ChildItem to find your txt files recursively in $dir path and then piping these FileInfo objects directly to Select-String cmdlet which accepts pipeline input and will grab the PSPath from the FileInfo object being passed to it and do its thing. Select-String will do this for every object that Get-ChildItem sends to it which are FileInfo objects for all txt files found recursively in your $dir path.
$dir = '/home/nicholas/Calibre Library/Microsoft Office User/549 (1476)'
Get-ChildItem -Recurse -Path $dir -Filter *.txt |
Select-String -Pattern '(?=.*?foo)(?=.*?bar)'

Answer 2

Get-ChildItem already does the recursion for you when you specify the -Recurse argument. For your code it doesn't make any difference. You get a linear list of all file informations that you can process using ForEach-Object in the same way as if you didn't specify -Recurse.
The SearchFile function should be executed when a ".txt" file is found.
Use the -Filter parameter to specify *.txt. Also when you want to get files only, always pass -File. This allows the filesystem provider to already skip directories, which is faster and also more correct (in theory there could be directories named e. g. foo.txt which would let SearchFile run into an error).
function tree($dir)
{
"$dir"
Get-ChildItem -Path $dir -Recurse -File -Filter *.txt | ForEach-Object {
SearchFile -dir $_.Directory.PSPath -file $_.Name
}
}
I don't know why your function SearchFile has separate parameters for directory and file name. The Get-ChildItem already outputs the full path in $_.PSPath. It doesn't make much sense to split the path apart and join it together again in SearchFile. I suggest you replace them by a single Path parameter.