Rename files by reformatting the date string embedded in their names

Question

I am using Windows' Powershell in the CMD to remove 'Mon, tue, wed' etc. from my filenames, which works perfectly

Get-ChildItem -recurse -name | ForEach-Object { Move-Item $_ $_.replace("Mon ", "") }
Get-ChildItem -recurse -name | ForEach-Object { Move-Item $_ $_.replace("Tue ", "") }
Get-ChildItem -recurse -name | ForEach-Object { Move-Item $_ $_.replace("Wed ", "") }
Get-ChildItem -recurse -name | ForEach-Object { Move-Item $_ $_.replace("Thur ", "") }
Get-ChildItem -recurse -name | ForEach-Object { Move-Item $_ $_.replace("Fri ", "") }
Get-ChildItem -recurse -name | ForEach-Object { Move-Item $_ $_.replace("Sat ", "") }

Now my file names look like this: 13 July 2018 - Lorem ipsum

I would like to switch the day with the month, so it will be: July 13 2018, so I could sort it by month. Or maybe even 2018 July 13.

How could I do this?

Thanks, Mike

Why not parse the date and re-output it in YYYY-MM-DD format? Months as names will not be (usefully) sortable. — Adrian Wragg, Mar 15 '19 at 12:14
Well they are downloaded files from the interwebz, which have the date of the blogarticle in the filename. So I would like to keep it simple and just switch the months and year etc. So I can sort it easily in my folder. — Mxkert, Mar 15 '19 at 12:26

mklement0 · Accepted Answer · 2019-03-15T14:09:06.597

You can combine both desired transformations into a single operation using Rename-Item with a delay-bind script block in which the -replace operator allows you to transform the file name as needed based on a regex (regular expression).

Get-ChildItem -Recurse -Name | Rename-Item -NewName {
  $_.Name -replace '\w+ (\d+) (\w+) (\d+)', '$3 $2 $1'
} -WhatIf

^{-WhatIf previews the renaming operation; remove it to perform actual renaming.}

An input file named Mon 13 July 2018 - Lorem ipsum, for instance, would be renamed to
2018 July 13 - Lorem ipsum.

^{Note: This sample file name happens to have no filename extension, but both the solutions above and below equally work with file names that do have extensions.}

For more information about PowerShell's -replace operator, see this answer.

If you wanted make your filenames truly sortable using an embedded format such as 2018-07-13 to represent 13 July 2018, more work is needed, via the -split operator:

Get-ChildItem -Recurse -Name | Rename-Item -NewName {
  # Split the name into the date part (ignoring the weekday) and the
  # rest of the file name.
  $null, $date, $rest = $_.Name -split '\w+ (\d+ \w+ \d+)'
  # Convert the date string to [datetime] instance, reformat it, and
  # append the rest.
  ([datetime] $date).ToString('yyyy-MM-dd') + $rest
} -WhatIf

An input file named Mon 13 July 2018 - Lorem ipsum, for instance, would be renamed to
2018-07-13 - Lorem ipsum.

For more information about PowerShell's -split operator, see this answer.
Assigning to multiple variables ($null, $date, $rest = ...) is explained in help topic about_Assignment_Operators

score 1 · Answer 2 · answered Mar 15 '19 at 14:45

Not an answer to your question, IMO mklement0's answer serves best.

But a replacement for your ~~ugly~~ suboptimal sample code.

The RegEx based -replace operator is superior to the .replace() method
when having alternations to replace.

[Globalization.DatetimeFormatInfo]::CurrentInfo.AbbreviatedDayNames

returns the abbreviated Day Names for the current locale, which can be combined
in one RegEx "(Sun|Mon|Tue|Wed|Thu|Fri|Sat) " with the code

$RE=[regex]"("+([Globalization.DatetimeFormatInfo]::CurrentInfo.AbbreviatedDayNames -join '|')+") "

Get-ChildItem -recurse -File | Rename-Item -NewName {$_.Name -replace $RE} -WhatIf

An empty replacement string doesn't need to expressed with the -replace operator.

If the output looks OK, remove the trailing -WhatIf

score 0 · Answer 3 · answered Mar 15 '19 at 12:49

You could chain replacements for each month and end with a replace statement to switch the numbers like this

"13 July 2018 - Lorem ipsum" `
    -replace 'July', '07' `
    -replace 'Aug', '08' `
    -replace "(\d+) (\d+) (\d+)", '$3 $2 $1'

wich returns

2018 07 13 - Lorem ipsum

score 0 · Answer 4 · answered Mar 15 '19 at 12:55

0

You can use following code to convert the date

$string = '13 July 2018 - Lorem ipsum'
$dateObject = [datetime]$string.Split('-')[0]
Write-Output "$($dateObject.ToString('yyyy MMMM dd')) - $($array[1])"

This will output

2018 July 13 -  Lorem ipsum

answered Mar 15 '19 at 12:55

Michael B.

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Rename files by reformatting the date string embedded in their names

4 Answers4