# Filtering: Where-Object and Comparisons Where-Object keeps only the objects that pass a test, such as every file over 1 MB or every song, and the test is written with comparisons read aloud as words, -eq "equals", -gt "greater than", -like "is like", with $\_ standing for this item. Apprentice · PowerShell · Operating System · Updated November 10, 2026 ## After this lesson you can - Keep only the objects you want with Where-Object, writing the test with $\_ for this item - Compare with -eq, -ne, -gt, -lt and -like, and say each one aloud ## Key takeaways - `Where-Object` lets through only the objects that pass a test, like a sieve. `Where-Object Length -gt 1MB` keeps every file over 1 MB. - Comparisons are words after a dash: `-eq` equals, `-ne` not equals, `-gt` greater than, `-lt` less than, and `-like` is like, with wildcards. - `$_` (read "this item") is the object being tested. In braces you can write `{ $_.Length -gt 1MB -and $_.Extension -eq '.mp4' }`. - Text comparisons ignore capital letters. `>` is not greater than: it means "into a file". Your phone says "Storage almost full", or a cloud backup refuses a file because it's too big. The first question is always the same: which files are over some size? File Explorer can sort a folder by size, but it can't answer "every file over 1 MB, in every folder, and nothing else". People sift lists like this all day: a teacher picks out the late assignments, a shop owner the orders over $100, an IT tech the programs using the most memory. This lesson uses the `drive` folder from *The Pipeline: |*. If you don't have it yet, run that lesson's practice-drive lines first, then `Set-Location ~\terminal-practice\drive`. ## Keep what passes a test: Where-Object A kitchen sieve lets the water through and keeps the pasta. `Where-Object` is a sieve for objects: it tests each one that arrives through the pipe and lets through only those that pass. You name a property, a comparison and a value: ```powershell Get-ChildItem -Recurse -File | Where-Object Length -gt 1MB | Select-Object Name, Length ``` ```text Name Length ---- ------ game-setup.exe 2355200 phone-backup.zip 1945600 unfinished-download.tmp 1126400 rain-sounds.mp3 1331200 road-trip-mix.mp3 1740800 birthday-party.mp4 1536000 graduation.mp4 2867200 ``` Read it aloud: "every file, where Length is greater than one megabyte." Seven of the eighteen files pass. A file's Length is counted in **bytes**, the smallest unit of a file's size; `1MB` is PowerShell's way of writing 1,048,576 of them, so you never count zeros. `1KB` and `1GB` work the same way. The `Select-Object` at the end only keeps the table narrow. ## The comparisons, read aloud Each comparison is a word after a dash, short for what you'd say: | Comparison | Read it | Example | |---|---|---| | `-eq` | equals | `Where-Object Extension -eq '.mp3'` | | `-ne` | not equals | `Where-Object Extension -ne '.tmp'` | | `-gt` | greater than | `Where-Object Length -gt 1MB` | | `-lt` | less than | `Where-Object Length -lt 100KB` | | `-like` | is like (with wildcards) | `Where-Object Name -like '*birthday*'` | `-ge` ("greater than or equal") and `-le` ("less than or equal") are there too. `-like` takes the wildcards from *Wildcards and Filters*, so `'*birthday*'` means "birthday anywhere in the name": ```powershell Get-ChildItem -Recurse -File | Where-Object Name -like '*birthday*' | Select-Object Name, Length ``` ```text Name Length ---- ------ birthday-cake.png 532480 birthday-party.mp4 1536000 ``` Text comparisons ignore capital letters, so `Where-Object Extension -eq '.MP3'` finds the three songs too. To make capitals count, put a `c` in front: `-ceq`, `-clike`. ## $\_: this item For a test with two parts, write it in braces. The braces hold a **script block**, a small piece of code that Where-Object runs once for each object. Inside it, `$_` (read "this item", or "dollar underscore") is the object being tested right now: ```powershell Get-ChildItem -Recurse -File | Where-Object { $_.Length -gt 1MB -and $_.Extension -eq '.mp4' } | Select-Object Name, Length ``` ```text Name Length ---- ------ birthday-party.mp4 1536000 graduation.mp4 2867200 ``` Read it aloud: "where this item's Length is greater than one megabyte, and this item's Extension equals .mp4." `-and` needs both parts to be true; `-or` needs one of them. `$_.Length` is the dot from *Properties and Methods*. `$PSItem` is a longer name for `$_`, and `where` and `?` are short names for Where-Object. The one mistake everybody makes: writing `>` for "greater than". In PowerShell `>` means "into a file", as in *Writing to Files: Set-Content, Add-Content and >*. `Where-Object { $_.Length > 1MB }` lets nothing through, and leaves a new file in your folder named `1048576`. Use `-gt`. (If you made that file, `Remove-Item 1048576` takes it away.) ## Running programs, and filtering early The same sieve works on anything. `Get-Process | Where-Object WorkingSet64 -gt 200MB` lists every running program using more than 200 MB of memory (`WorkingSet64` is how much memory a program is using right now). Try it: the list is your own computer's, so no two people see the same one. When you only need files by name, `Get-ChildItem -Filter`, from *Wildcards and Filters*, is faster, because Windows does the sifting before PowerShell sees a file. Where-Object is for everything else: size, date, anything an object knows. Windows PowerShell 5.1 runs all of this the same way. On a Mac or Linux, `-eq` still ignores capital letters, but file names themselves care about them. **Try it.** List every file on the drive smaller than 100 KB. Then every photo: `.jpg` or `.png`, written with `-or`. ## Check yourself 2 questions to try on the lesson page. ## So what Where-Object turns "find me the ones that…" into one line: name the fact, the comparison and the value, and only what passes gets through. ## Key terms - [Where-Object](https://www.ask-codey.com/glossary/where-object) - [Comparison Operators](https://www.ask-codey.com/glossary/comparison-operators-powershell) - [Script Block](https://www.ask-codey.com/glossary/script-block) - [$\_ and $PSItem](https://www.ask-codey.com/glossary/and-psitem) - [Byte](https://www.ask-codey.com/glossary/byte) ## Cheat sheets - [Filtering: Where-Object and Comparisons](https://www.ask-codey.com/cheat-sheets/powershell-where-object-cheat-sheet) ## Related - [The Pipeline: |](https://www.ask-codey.com/lessons/powershell-the-pipeline) - [Sorting: Sort-Object](https://www.ask-codey.com/lessons/powershell-sort-object) - [Wildcards and Filters](https://www.ask-codey.com/lessons/powershell-wildcards-and-filters) Source: https://www.ask-codey.com/lessons/powershell-where-object