renaming with regex in powershell

usecase

the puzzle is, how to rename a bunch of file with a certain criteria. In my case, i have the following structure (snippet) and I need to remove all the digits from the name

├───FOO
│       loremIpsum02_NEECA_Northern_Europe.xlsx
│       loremIpsum03_NEECA_Czech_Republic.xlsx
│       loremIpsum04_NEECA_Hungary.xlsx
│       loremIpsum05_NEECA_Poland.xlsx
│       loremIpsum06_NEECA_Romania.xlsx
│       loremIpsum07_NEECA_Bulgaria_Greece.xlsx
│       loremIpsum08_NEECA_Georgia.xlsx
│       loremIpsum09_NEECA_Kazakhstan.xlsx
│       loremIpsum10_NEECA_Russia.xlsx
│       loremIpsum29_NEECA_All.xlsx
│
├───BAR
│       loremIpsum17_AEM_Turkey.xlsx
│       loremIpsum18_AEM_Egypt.xlsx
│       loremIpsum19_AEM_Morocco_Mauretania.xlsx
│       loremIpsum20_AEM_Africa 1.xlsx
│       loremIpsum21_AEM_Africa 2.xlsx
│       loremIpsum22_AEM_Africa 3.xlsx
│       loremIpsum31_AEM_All.xlsx

1. mass renaming get-childitem (dir)

get-childitem -recurse | Rename-Item -NewName {$_.Name -replace '\d{2}', ''}

• pipe get-childitem (list content) with the recurse parameter (include the content of all subfolders) with the rename-item cmdlet
• no loop structure necessary here (such as foreach-object)
• the value of NewName is a script block that runs before the value is submitted to the NewName parameter
• in the script block, the $_ the automatic variable represents each file object as it comes to the command through the pipeline
• here, you use the -replace switch and regex literal to replace the 2 digits with an empty string
• of course, '\d{2} can be replaced with any regex literal according to the current need

├───FOO
│       loremIpsum_NEECA_Northern_Europe.xlsx
│       loremIpsum_NEECA_Czech_Republic.xlsx
│       loremIpsum_NEECA_Hungary.xlsx
│       loremIpsum_NEECA_Poland.xlsx
│       loremIpsum_NEECA_Romania.xlsx
│       loremIpsum_NEECA_Bulgaria_Greece.xlsx
│       loremIpsum_NEECA_Georgia.xlsx
│       loremIpsum_NEECA_Kazakhstan.xlsx
│       loremIpsum_NEECA_Russia.xlsx
│       loremIpsum_NEECA_All.xlsx
│
├───BAR
│       loremIpsum_AEM_Turkey.xlsx
│       loremIpsum_AEM_Egypt.xlsx
│       loremIpsum_AEM_Morocco_Mauretania.xlsx
│       loremIpsum_AEM_Africa 1.xlsx
│       loremIpsum_AEM_Africa 2.xlsx
│       loremIpsum_AEM_Africa 3.xlsx
│       loremIpsum_AEM_All.xlsx

2. single rename with get-item

• what I do is that I keep todo in a git repo of markdown files
• all of the files begin with a timestamp yyyy-MM-dd, e.g. 2020-10-26
• with a simple alias u and the filepath, I update the old date to the new date

function update-timestamp ($file) {
    $today = Get-Date -Format yyyy-MM-dd
    $regex = '\d{4}-\d{2}-\d{2}'
    gi $file | ren -NewName {$_.Name -replace $regex, $today} -Verbose
}

3. sources

• ms | example 4
• stackoverflow