How to rename multiple files keeping brackets - Powershell

Question

I am trying to remove any words before content inside [*]

I have multiple files to rename for example 'ABC [1].txt, ABC [2].txt, ABC [3].txt' that I need to rename to '[1].txt, [2].txt, [3].txt'

I have a few hundred items to rename and wondered if this can be done in powershell.

However I can not find any information on doing this. Does anybody have any ideas? Thanks!

Answer 1

This can be achieved by an easy regex replace:

$sourceFolder = "C:\path\to\your\dir"

Get-ChildItem -Path $sourceFolder -Filter "*[*" | ForEach-Object {
    $newName = $_.Name -replace '.*(\[\d+\].*)', '$1'
    Rename-Item -Path $_.FullName -NewName $newName
}

Explanation of the regex used:

• .* - match 0 or more of any character.
• (\[\d+\].*) - Capturing group capturing 1 or more digits which are enclosed in [] followed by the ext-name.
• $1 - is the substitution string which is captured above.

Answer 2

Use Rename-Item with a delay-bind script block, in which you can dynamically determine the new name for each given file based on its existing name ($_.Name) and outputting the new one.

In your case, the regex-based -replace operator allows you to remove everything before the (last) [ from the file name:

Get-ChildItem *.txt |
  Rename-Item -NewName { $_.Name -replace '^.+ (?=\[)' } -WhatIf 

^{Note: The -WhatIf common parameter in the command above previews the operation. Remove -WhatIf and re-execute once you're sure the operation will do what you want.}

Note:

• The above could result in duplicate target file names, and handling this case would require extra work.

• Not specifying a replacement operand with -replace is the same as specifying the empty string, which effectively removes what was matched.

  • E.g., 'foo' -replace 'o' is the same as 'foo' -replace 'o', '': both result in 'f'

• You could make the regex more robust, if needed; e.g.:

  • $_.Name -replace '^.+ (?=\[\d+\]\.txt$)'

    • For an explanation of the regex and the option to experiment with it, see this regex101.com page.

  • Or - to demonstrate handling the base file name and its extension separately:

    • ($_.BaseName -replace '^.+ (?=\[\d+\]$)') + $_.Extension

• Input file names that don't match the regex cause -replace to return the input string as-is, which in turn causes New-Item to quietly skip such files (trying to rename a file to its existing name is a quiet no-op).

  • However, note that as of PowerShell 7.4.0 this only works with files, and not also with renaming directories, where an attempt to rename to the existing name causes an error.
  • Treating directories the same as files (quiet no-op if the new name is the same as the old) is the subject of GitHub issue #14903, which has been green-lit, but no one has stepped up to implement it yet.