How to loop through files and rename using PowerShell?

Question

I would like to rename all the jpg files in a folder to uniform convention like Picture00000001.jpg where 00000001 is a counter.

It would be a walk in the park in C# but I would think this is the kind of bread and butter stuff that PowerShell was made for.

I'm guessing something like

$files = ls *.jpg
$i=0
foreach($f in $files) { Rename-Item $f -NewName "Picture"+($i++)+".jpg" }

But before I hit the gas on this I would like to 1) format the counter, and 2) have some sense that this is in fact even a good idea.

If this sounds more like OCD than a good idea please speak up.

Keith Hill · Accepted Answer · 2009-10-06 15:13:02Z

25

You can do this fairly simply in PowerShell:

ls *.jpg | Foreach -Begin {$i=1} `
   -Process {Rename-Item $_ -NewName ("Picture{0:00000000}.jpg" -f $i++) -whatif}

If you're looking for the "basename" and if you're on PowerShell 2.0 just use the Basename property that PowerShell adds to each FileInfo object:

ls *.jpg | Format-Table Basename

Note that on PowerShell 1.0, the PowerShell Community Extensions adds this same Basename property.

If the intent is to append a counter string to the file's basename during the rename operation then try this:

ls *.jpg | Foreach {$i=1} `
   {Rename-Item $_ -NewName ("$($_.Basename){0:00000000#}.jpg" -f $i++) -whatif}

edited Oct 6, 2009 at 15:13

answered Oct 6, 2009 at 0:33

Keith Hill

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5 Comments

Ralph Shillington Over a year ago

Sorry for the disconnect between title and question -- I've changed the title.

Joey Over a year ago

Whoa, you can give a begin and process script block individually to ForEach-Object? I have to revisit some golfed PE problems.

Joey Over a year ago

Hm, I just wonder why this works. The documentation says nothing about the -Begin and -End parameters to ForEach-Object being positional. Magic?

Keith Hill Over a year ago

Yes, I was using the parameters -begin and -process implicitly so I updated one example to state this explicitly. Normally when you use Foreach, you are "positionally" using the -Process parameter for the scriptblock you provide. Not sure how the positional "magic" works in the Begin/End case but it is has been this way since the early days.

Joey Over a year ago

Ah, I just was a little confused. It's clear what two (or three) scriptblocks do, but help % -param begin only tells me that "named" is the only possibility here. Neither are there examples or other documentation in help % for that case. That's why I was wondering. But nice to know that this works.

Ste · Accepted Answer · 2021-06-16 19:49:25Z

2

Try this to get the FilenameWithOutExtension

$f.DirectoryName + "\" + $f.BaseName

edited Jun 16, 2021 at 19:49

Ste

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answered Oct 6, 2009 at 0:24

Brent

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