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MrDrMcCoy
Asked: 2012-09-18 14:16:30 +0800 CST

PowerShell overwrites source variable when I create new concatenated variable

  • 772

I have a large script that will be asking for a download directory and downloading a bunch of files into it. However, when I set the download filename string based on the directory string, they are both overwritten with the full filename string. Here's what I mean:

$dldir = 'c:\downloads'
$dlfile = $dldir += '\data.csv'

This results in both $dldir and $dlfile to be set to "c:\downloads\data.csv". Obviously, since I want to reuse $dldir to set $dlfile multiple times in the script, I don't want it to change. Does anyone know how to do this?

Thanks.

powershell

2 Answers

  1. Best Answer

    Instead of:

    $dlfile = $dldir += '\data.csv'

    use:

    $dlfile = $dldir + '\data.csv'
    • 1

  2. Another option would be to use Join-Path

    $dlfile = Join-Path $dldir '\data.csv'

    The benefit of Join-Path is that you don't have to worry about leading or trailing slashes.. the command will clean that up for you and give you a nice clean file path.

    So 

    $dlfile = Join-Path $dldir 'data.csv'

    or

    $dldir = 'c:\downloads\'
$dlfile = Join-Path $dldir '\data.csv'

    or

    $dldir = 'c:\downloads\'
$dlfile = Join-Path $dldir '\data.csv'

    would all turn out with a valid path. This is very useful if you are taking user input for the file location and don't want to worry about sanitizing the input for trailing slashes.

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