Merging multiple CSV files into one using PowerShell

Hello I'm looking for powershell script which would merge all csv files in a directory into one text file (.txt) . All csv files have same header which is always stored in a first row of every file. So I need to take header from the first file, but in rest of the files the first row should be skipped. I was able to find batch file which is doing exactly what I need, but I have more than 4000 csv files in a single directory and it takes more than 45 minutes to do the job.

@echo off
ECHO Set working directory
cd /d %~dp0
Deleting existing combined file
del summary.txt
setlocal ENABLEDELAYEDEXPANSION
set cnt=1
for %%i in (*.csv) do (
 if !cnt!==1 (
 for /f "delims=" %%j in ('type "%%i"') do echo %%j >> summary.txt
) else (
 for /f "skip=1 delims=" %%j in ('type "%%i"') do echo %%j >> summary.txt
 )
 set /a cnt+=1
 )

Any suggestion how to create powershell script which would be more efficient than this batch code?

Thank you.

John

Solution

This will append all the files together reading them one at a time:

get-childItem "YOUR_DIRECTORY\*.txt" 
| foreach {[System.IO.File]::AppendAllText
 ("YOUR_DESTINATION_FILE", [System.IO.File]::ReadAllText($_.FullName))}

# Placed on seperate lines for readability

This one will place a new line at the end of each file entry if you need it:

get-childItem "YOUR_DIRECTORY\*.txt" | foreach
{[System.IO.File]::AppendAllText("YOUR_DESTINATION_FILE", 
[System.IO.File]::ReadAllText($_.FullName) + [System.Environment]::NewLine)}

Skipping the first line:

$getFirstLine = $true

get-childItem "YOUR_DIRECTORY\*.txt" | foreach {
    $filePath = $_

    $lines =  $lines = Get-Content $filePath  
    $linesToWrite = switch($getFirstLine) {
           $true  {$lines}
           $false {$lines | Select -Skip 1}

    }

    $getFirstLine = $false
    Add-Content "YOUR_DESTINATION_FILE" $linesToWrite
    }