Bulk renaming of files in PowerShell with sequential numeric suffixes

Question

I have 14,000 pictures sorted into files by year and month but taken with multiple cameras and I want the file name to reflect the date taken. For example October 16, 1998 pictures are in a folder called 1998\10 October\19981016.

I want the all the pictures to be named 19981016_0001 19981016_0002 etc. I tried multiple suggestions but it hasn't worked.

I can get to the point where it lists the folder I want to change but I'm unable to actually change it. All of my pictures are .jpg.

Attempts I created a temp file of copies in case I messed it up. I started by typing cd "C:\Documents and Settings\Brooke LastName\Desktop\Temp" then after successfully getting my file to load I used a formula I found on this forum.

ls *jpg | Foreach {$i=1} {Rename-Item _ -NewName ("$($.19981016){0:00000000#} .jpg" -f $i++) -whatif}

The error I got said

Unexpected token ' .19981016' in expression or statement.

At line:1 char:12 + $.19981016 <<<<

The error repeated several times.

I found several formulas on the web but most created files that would number with parentheses for example vacation (1).jpg. I want a four digit counter after an underscore at the end of my date, e.g. 19981016_0001

Answer 1

The syntax is way off. A few issues:

• I'm not sure what $($.19981016) was intended to produce, but $( ) evaluates the expression in the parentheses and interpolates the result into the string, and you're getting the error because $.19981016is not a valid expression. The error would be repeated for each .jpg file in the directory.
• {0:00000000#} in a formatted string will create a zero-padded number of 9 digits, but a shorter way to do that is {0:D9}. However, I thought you wanted the zero-padded number to have 4 digits, so that should be {0:0000#} or {0:D4}.
• I'm not sure what Foreach {$i=1} { [...] is supposed to do. The keyword foreach can mean a foreach loop, or it can be shorthand for Foreach-Object. In this context, receiving input from a pipeline, it's necessarily the latter, but this syntax is incorrect either way.

This will do what you want, if I understand the description correctly:

$i = 1
Get-ChildItem *.jpg | %{Rename-Item $_ -NewName ('19981016_{0:D4}.jpg' -f $i++)}

The filenames will be 19981016_0001.jpg, 19981016_0002.jpg, 19981016_0003.jpg, etc.

A few notes:

• You said that you want filenames like 19981016_0001, but I'm assuming you want to keep the .jpg extension.
• You need to initialize $i, otherwise it will start from 0 if it's not yet defined, or worse yet, from some other number if $i was used previously in the same PowerShell session. For example, if you have 1,432 .jpg files in the directory, and you run the command first with -WhatIf, and then run it for real, the numbers will start from 1432.
• $i++ increments $i by 1. However, if you're using it as a value, it increments after the value is read; that's why if $i is undefined, it will start from 0.
• Get-ChildItem is the same as ls. I used the native PowerShell name, but they're interchangeable (ls, dir, and gci are all aliases for Get-ChildItem).
• %{ } is shorthand for Foreach-Object