Powershell script to automate gci - powershell

Question

I'm tying to automate gci in order to work on each row in a config file, where for each row I have as first column the path, and following it a list of files. Something like this:
C:\Users\*\AppData\Roaming\* *.dll
C:\Test file.txt,file2.txt
This means that gci will search for:
*.dll in C:\Users*\AppData\Roaming*
file.txt in C:\Test
file2.txt in C:\Test
In order to do this I'm creating dynamically the where condition in the script below. Here the ps script I'm using
foreach($line in Get-Content .\List.txt) {
try {
$path,$files = $line.split(' ')
$files = $files.split(',')
}
catch {
$path = $line
$files = "*.*"
}
if([string]::IsNullOrEmpty($files)){
$files = "*.*"
}
$filter = $files -join(" -or `$_.Name` -like ")
$filter = "`$_.Name` -like " + $filter
echo "Searching Path: $path, Pattern: $filter" | out-file -append -encoding ASCII -filepath .\result.txt
if ($path.Contains("*"))
{
gci -Path $path -Recurse | Where {$filter} | Select -ExpandProperty FullName | Out-String -Width 2048 | out-file -append -encoding UTF8 -filepath .\result.txt
}
else
{
gci -Path $path | Where {$filter} | Select -ExpandProperty FullName | Out-String -Width 2048 | out-file -append -encoding UTF8 -filepath .\result.txt
}
}
The problem is that the where filter is not considered. All files are returned
First attempt, suggested by
foreach($line in Get-Content .\List.txt) {
try {
$path,$files = $line.split(' ')
$files = $files.split(',')
}
catch {
$path = $line
$files = "*.*"
}
if([string]::IsNullOrEmpty($files)){
$files = "*.*"
}
$filter = $files -join(" -or `$_.Name -like ")
$filter = "`$_.Name -like " + $filter
$gciParams = #{
Path = $Path
Recurse = $Path.Contains('*')
}
"Searching Path: $path, Pattern(s): [$($files -join ',')]" | Add-Content -Path .\result.txt -Encoding ASCII
Get-ChildItem #gciParams | Where $filter | Select -ExpandProperty FullName | Add-Content -Path .\result.txt -Encoding UTF8
}

Answer 1

If you want to create a piece of code and defer execution of it until later, you need a Script Block.
A Script Block literal in PowerShell is just {}, so for constructing script block to filter based on a single comparison, you'd want to define $filter like this:
$filter = {$_.Name -like $filter}
At which point you can pass it directly as an argument to Where-Object:
Get-ChildItem $path |Where-Object $filter
... but since you want to test against multiple wildcard patterns, we'll need to write a slightly different filtering routine:
$filter = {
# Store file name of file we're filtering
$FileName = $_.Name
# Test ALL the patterns in $files and see if at least 1 matches
$files.Where({$FileName -like $_}, 'First').Count -eq 1
}
Since the $filter block now references $files to get the patterns, we can simplify your loop as:
foreach($line in Get-Content .\List.txt) {
try {
$path,$files = $line.split(' ')
$files = $files.split(',')
}
catch {
$path = $line
$files = "*.*"
}
if([string]::IsNullOrEmpty($files)){
$files = "*.*"
}
$gciParams = #{
Path = $Path
Recurse = $Path.Contains('*')
}
"Searching Path: $path, Pattern(s): [$($files -join ',')]" | Add-Content -Path .\result.txt -Encoding ASCII
Get-ChildItem #gciParams | Where $filter | Select -ExpandProperty FullName | Add-Content -Path .\result.txt -Encoding UTF8
}
Note that we no longer need to re-define $filter everytime the loop runs - the condition is based on the value of $files at runtime, so you can define $filter once before entering the loop and then reuse $filter every time.
The "trick" with using #gciParams (which allows us to remove the big if/else block) is known as splatting, but you could achieve the same result with Get-ChildItem -Path:$Path -Recurse:$Path.Contains('*') :)