I have a specific date "2021/11/28", i want the list of files from example filenames(below) whose file name is greater than 2021/11/28. remember not the creation time of the file names.

 "test_20211122_aba.*"
 "abc_20211129_efg.*"
 "hij_20211112_lmn.*" 
 "opq_20211130_rst.*"

I'm expecting to get

 "abc_20211129_efg.*"
 "opq_20211130_rst.*"

Really appreciate your help.

CodePudding user response：

You don't strictly need to parse your strings into dates ([datetime] instances): Because the date strings embedded in your file names are in a format where their lexical sorting is equivalent to chronological sorting, you can compare the string representations directly:

# Simulate output from a Get-ChildItem call.
$files = [System.IO.FileInfo[]] (
  "test_20211122_aba1.txt",
  "abc_20211129_efg2.txt",
  "hij_20211112_lmn3.txt",
  "hij_20211112_lmn4.txt",
  "opq_20211130_rst5.txt"
)

# Filter the array of files.
$resultFiles = 
  $files | Where-Object {
    $_.Name -match '(?:^|.*\D)(\d{8})(?:\D.*|$)' -and
      $Matches[1] -gt ('2021/11/28"' -replace '/')
   }

# Print the names of the filtered files.
$resultFiles.Name

• $_.Name -match '(?:^|.*\D)(\d{8})(?:\D.*|$)' looks for (the last) run of exactly 8 digits in each file name via a capture group ((...)), reflected in the automatic $Matches variable's entry with index 1 ($Matches[1]) afterwards, if found.

• '2021/11/28"' -replace '/' removes all / characters from the input string, to make the format of the date strings the same. For brevity, the solution above performs this replacement in each loop operation. In practice, you would perform it once, before the loop, and assign the result to a variable for use inside the loop.