Comparing two files or two folders

Compare A vs B puts two files, or two folders, side by side and tells you what differs. It works on its own: it does not need a scan, and it does not change the scan you have open.

Before you start

Protected folders are not checked here. A comparison is outside the app's normal handling, so anything you discard on this screen can be sent to the Recycle Bin even if it sits in a folder you protected in Settings. Nothing goes until you confirm, and the Recycle Bin can give it back.

Step 1 · Choose A and B

Select Compare in the title bar and choose Compare A vs B….

For each side, choose Browse file… or Browse folder…. Until a side is chosen it reads "Not chosen yet".

Pick two files or two folders. A file and a folder cannot be compared:

"Choose two files or two folders. A file cannot be compared with a folder."

Then choose Compare.

Comparing two folders

Trawler reads both folders ("Reading the two folders…") and pairs each file in A with the file at the same place in B — A\photos\beach.jpg with B\photos\beach.jpg. Files are not matched by content across different names or folders. Upper and lower case in names do not matter.

The line above the list counts the result:

"2 identical, 3 different, 1 only in A, 1 only in B, 0 could not be read"

Each row in the list shows one of these:

Status What it means
Identical Same content, byte for byte. On a folder: everything inside it is identical.
Different The two files differ. On a folder: something inside it differs or is missing on one side.
Only in A / Only in B The file or folder exists on one side only.
Could not be read The two files are the same size but one could not be read, so they could not be compared.

Differences only is ticked when the comparison opens, so identical files are hidden. Untick it to see everything.

Looking at a pair

Choose a file in the list to see A and B side by side. Images, videos, audio and documents open in the same compare views as the Similar tabs, and their tools appear on this screen's ribbon. See Reviewing similar results. Other files open side by side as previews.

The arrows in the compare view step to the next or previous pair in the list. A file that exists on one side only says so: "This file exists only in A."

Comparing two files

With two files there is no list. You get the pair, and one line answers the question:

  • "The two files are identical."
  • "The two files are different."
  • "One of the files could not be read, so they cannot be compared."

Discarding and recycling

Discarding marks a file to go; nothing is removed until you recycle.

Command What it does
Discard in A / Discard in B Marks or unmarks that side of the selected row. Discard and Keep in the compare view do the same.
Discard all duplicates in A Marks the A copy of every identical pair. Files that differ are never touched.
Discard all duplicates in B The same for the B copies.
Recycle discarded (N) Sends the marked files to the Recycle Bin, after you confirm.

A marked row shows Discard A, Discard B or Discard A and B. With two files, the Discard all commands are available only when the two are identical.

Recycle discarded asks first:

"Send 3 discarded files to the Recycle Bin?"

Choose Recycle to go ahead. Afterwards a folder comparison is read again, so the list shows what is now there; any marks that were not recycled are cleared. With two files, a side that was recycled is gone and the other is shown on its own; if one could not be recycled, the screen says "The comparison failed: …" with the reason.

To get a file back, restore it from the Windows Recycle Bin.

Notes

  • Close comparison ends the comparison and discards any marks you have not recycled.
  • Trawler never recycles anything inside $RECYCLE.BIN or System Volume Information, or its own working files.