Rename files in a specific way. Target nth string between symbols

Question

Apologies in advance for a bit vague question (no coding progress).

I have files (they can be .csv but dont have .csv, but that I can add via script easy). The files' name is something like this:

TRD_123456789_ABC123456789_YYMMDD_HHMMSS_12345678_12345_blabla_blabla_blabla_blabla

Now I would need a script that renames the file in a way that it keeps original name except:

1. It would cut off the ending (blabla_blabla_blabla_blabla) part.
2. Changes the 12345 before blabla to random 5 characters (can be numbers too)
3. Change timestamp of HHMMSS to current Hours, minutes, seconds.

In regards to point 3. I think that I can insert arbitary powershell script to any string in " " queotes. So when renaming the files, I was thinking I could just add

Rename-Item -NewName {... + $(get-date -f hhmmss) + ...}

However, I am lost how to write renaming script that renames parts between 4th & 5th _ symbol. And removes string part after 7th _ symbol.

Can somebody help me with the script or help me how to in powershell script target string between Nth Symbols?

Kind Regards, Kamil.

Answer 1

Split the string on _:

$string = 'TRD_123456789_ABC123456789_YYMMDD_HHMMSS_12345678_12345_blabla_blabla_blabla_blabla'

$parts = $string -split '_'

Then discard all but the first 6 substrings (eg. drop the 12345 part and anything thereafter):

$parts = $parts[0..5]

Now add your random 5-digit number:

$parts = @($parts; '{0:D5}' -f $(Get-Random -Maximum 100000))

Update the string at index 4 (the HHMMSS string):

$parts[4] = Get-Date -Format 'HHmmss'

And finally join all the substrings together with _ again:

$newString = $parts -join '_'

Putting it all together, you could write a nice little helper function:

function Get-NewName {
  param(
    [string]$Name
  )

  # split and discard
  $parts = $Name -split '_' |Select -First 6

  # add random number
  $parts = @($parts; '{0:D5}' -f $(Get-Random -Maximum 100000))

  # update timestamp
  $parts[4] = Get-Date -Format 'HHmmss'

  # return new string
  return $parts -join '_'
}

And then do:

Get-ChildItem -File -Filter TRD_* |Rename-Item -NewName { Get-NewName $_.Name }