How can I bulk rename files in PowerShell?

Question

I'm trying to do the following: ``` Rename-Item c:\misc\*.xml *.tmp ``` I basically want to change the extension on every files within a directory to `.tmp` instead of `.xml`. I can't seem to find a straight forward way to do this in PowerShell.

Accepted Answer

From example 4 in the help documentation of `Rename-Item` retrieved with the command:

```
get-help Rename-Item -examples
```

Example:

```
Get-ChildItem *.txt| Rename-Item -NewName { $_.Name -replace '\.txt','.log' }
```

Note the explanation in the help documentation for the escaping backslash in the replace command due to it using regular expressions to find the text to replace.

To ensure the regex `-replace` operator matches only an extension at the end of the string, include the regex end-of-string character `$`.

```
Get-ChildItem *.txt | Rename-Item -NewName { $_.Name -replace '\.txt$','.log' }
```

This takes care of the case mentioned by @OhadSchneider in the comments, where we might have a file named `lorem.txt.txt` and we want to end up with `lorem.txt.log` rather than `lorem.log.log`.

Now that the regex is sufficiently tightly targeted, and inspired by @etoxin's answer, we could make the command more usable as follows:

```
Get-ChildItem | Rename-Item -NewName { $_.Name -replace '\.txt$','.log' }
```

That is, there is no need to filter before the pipe if our regex sufficiently filters after the pipe. And altering the command string (e.g. if you copy the above command and now want to use it to change the extension of '.xml' files) is no longer required in two places.

How can I bulk rename files in PowerShell?

Solution

Problem