Redo of a script in reply to https://www.reddit.com/r/PowerShell/comments/3zqexe/i_want_to_search_multiple_csv_files_for_a/

reddit-u-tehreet-csv-search.ps1

param (
    [Parameter(Mandatory=$True,Position=1)] $UserName,
    $SharePath = "\\vsnhq1coap01mes\HomeMDB",
    $CsvsToSearch = 1
)

# From CSV which lists Exchange server for each store,
# Create a lookup hash table
$StoreServer = @{}
Import-Csv -Path "store-server.csv" |
    ForEach-Object { $StoreServer[$_.Store] = $_.Server }

if (Test-Path $SharePath) {
    Get-ChildItem -Path $SharePath |
        Sort CreationTime -Descending |
        Select -First $CsvsToSearch -ExpandProperty FullName |
        ForEach-Object {
            $CSVFilePath = $_
            $MiniCsv = New-Object System.Collections.ArrayList
            # Get the CSV header row
            $MiniCsv.Add((Get-Content -Path $CSVFilePath -TotalCount 1)) | Out-Null
            # Add any rows matching $UserName
            Get-Content $CSVFilePath |
                Select-String -SimpleMatch $UserName |
                ForEach-Object { $MiniCsv.Add($_) | Out-Null }
            $CsvData = ($MiniCsv | Out-String | ConvertFrom-Csv)
            $CSVData |
                Where-Object {$_."user id" -eq $UserName} |
                Select-Object "User ID",Mail,Store, @{Name = "Exchange Server"; Expression = {$StoreServer[$_.Store]}}
        }
}

store-server.csv

This script hurt me the last time around. Here is how I might have done it.

First, I put the store/server information into CSV format which really should probably be a separate file. Then after importing or converting the csv I make a hash out of it so $StoreServer["storename"] is the Exchange server which makes our logic much easier.

Then I saw my comment from the previous thread about 40k-line CSVs and /u/mystikphish 's Select-String suggestion and took a page from his/her book. First I capture the header row of the csv into an arraylist, then I use Select-String to capture any lines containing the username into the arraylist. Then I pipe the arraylist into Out-String and then to ConvertFrom-Csv, so I'm not converting the entire CSV to search for presumably one line.

Then instead of parsing the data more than once I just select the items desired plus a calculated field using the hash store/server lookup.

Also, parameters. Call the script with -CsvsToSearch 2 to search the two most recent CSVs.