How to Detect What Changed in a Folder

• →Baseline now, verify later — that's the whole idea.
• →Checksums catch edits that timestamps miss.
• →Detects added and deleted files, not just changed ones.
• →Schedule it and get told only when something drifts.

Why dates and filenames fail

The instinct is to sort by "date modified" and scan for anything recent. It feels right and it's quietly unreliable:

• ·Timestamps can be preserved. Plenty of tools rewrite a file's contents while keeping its original modified date — the change is real, the date says nothing happened.
• ·Timestamps can be reset. Copies, syncs, and restores routinely stamp everything with the same "now," burying real changes in noise.
• ·Filenames don't reflect contents. The same name can hold completely different bytes — a replaced logo, an edited spreadsheet, a swapped config.
• ·You can't eyeball additions. One new file dropped into a folder of thousands is invisible to a manual scan.

The only thing that reliably reflects "did this file change?" is the file's actual content — and that's what a checksum measures.

The baseline idea

A checksum is a short fingerprint computed from a file's contents — change one byte and the fingerprint changes completely (see verifying folder integrity with checksums). A manifest is just a list of those fingerprints for every file in a folder, captured at one moment you trust.

That manifest is your baseline. Detecting changes then becomes a simple question: does the folder still match its baseline? This is different from comparing two folders — you're not comparing folder A to folder B, you're comparing this folder to its own earlier self.

Three kinds of change a baseline catches

That third row is the one most tools miss. A plain sha256sum -c only re-checks the files in its list, so a newly added file slips by. Catching additions needs a full-folder comparison.

How to do it

With the FolderManifest CLI it's two commands. First, capture the baseline while the folder is good:

foldermanifest generate "C:\Project" --format json --out project-baseline

Later — a day, a week, after a handoff — verify the folder against that baseline. The report lists every added, removed, and modified file, and the command exits 0 if nothing changed, 1 if anything did:

foldermanifest verify "C:\Project" --manifest project-baseline.json

Verify: 3 changes since baseline.
  modified  reports/q3.xlsx
  added     notes/new-draft.docx
  removed   config/old.yml

That's the reliable answer to "what changed in this folder?" — contents-based, complete, and repeatable. It works the same on Linux; on Windows you can also reach for PowerShell Get-FileHash for one-off file checks.

Monitor a folder automatically

Detecting changes once is useful; getting told about them is better. Because verify returns a clean exit code, you can schedule it and alert only on drift — silence on a clean night, a message the moment something moves:

foldermanifest verify "C:\Project" --manifest project-baseline.json --quiet
# exit 0 -> do nothing; exit 1 -> send an alert

The full scheduled setup — Windows Task Scheduler, exit-code alerting, and watching many folders at once — is in automate folder verification with the CLI.

Prefer a click, not a command?

The same workflow lives in the FolderManifest desktop app: open a folder, generate a manifest, and run a verify whenever you want a readable report of what's changed — added, edited, and deleted files, with a clear summary you can save or share. The command line is there when you want to automate it; the app is there when you just want to look.