How to make Powershell script to execute git command

This script should do exactly what you want

• Search recursively from a root directory
• Exclude files with existing "yyyyMMdd " file name prefix
• Rename the files not excluded above with ""yyyyMMdd " file name prefix based on their specific LastWriteTime

Warning: You should test this script first because renaming could be dangerous. Remove the # in front of Rename-Itemafter you have verified that only intentional files will be renamed.

Long version

$folder = "C:\somefolder"
$files = get-childitem -path $folder -recurse | where { -not $_.PSIsContainer }
[datetime]$dirDate = New-Object DateTime

foreach ($file In $files) {

    $strDate = $file.Name.substring(0,8)

    if (-Not [DateTime]::TryParseExact($strDate, "yyyyMMdd", 
        [System.Globalization.CultureInfo]::InvariantCulture, 
        [System.Globalization.DateTimeStyles]::None, [ref]$dirDate)) {

        $newName = $file.lastwritetime.tostring("yyyyMMdd ") + $file.name
        echo $newName
        #Rename-Item -path $file.Fullname -newname $newName
    }   
}

Short version

[datetime]$dirDate = New-Object DateTime

dir "C:\somefolder" -r | ? { ! $_.PSIsContainer } | % {          

    if ( ! [DateTime]::TryParseExact($_.Name.substring(0,8), "yyyyMMdd", 
        [System.Globalization.CultureInfo]::InvariantCulture, 
        [System.Globalization.DateTimeStyles]::None, [ref]$dirDate)) {

        $newName = $_.lastwritetime.tostring("yyyyMMdd ") + $_.name
        echo $newName
        #Ren $_.Fullname $newName
    }
}

Used stackoverflow answers

• [DateTime]::TryParseExact to test if the first 8 characters can be a valid date
• $_.lastwritetime.tostring("yyyyMMdd ") to format the lastwrite stamp

Setting the credential.helper config option to store should definitely do what you're asking for. You'll still have to enter your username and password at least once for git-credential-store to store it in a file (~/.git-credentials by default), but then you shouldn't need to anymore.

Note that the file storing your credentials won't be encrypted and anybody managing to read it would then get the user's permissions on the repository, so it might a good idea to set up a read-only user especially for this and not globally set the credential.helper config option to store.

If you're using a web interface to your repository (Github, Bitbucket, Gitlab, etc), you might also have the (preferred, imho) possibility to set up a SSH deploy key through the repository settings to provide secure, read-only access.