I am looking for a tool that is able to compare directories, not only files. Also it is important to be able to call the tool from the command line.
It would be great to have a free tool, if not free please specify the price.
For all the googlers... check out Beyond Compare it rules. Costs 30$ or 50$ for Pro version.
FileMerge (free), shipped with Xcode, offers a directory view.
A command line version is available through the Terminal application opendiff.
Diffmerge should meet all your requirements.
If you don't mind using the terminal, the
diff command can compare directories.
This utility is also available in most Linux distributions.
diff -rq directory1/ directory2/
-r indicates recurse through subdirectories, and
-q gives brief output (i.e. don't show the actual diffs, just note what files/dirs are different).
Other useful options are:
-s report identical files,
-i ignore case in file contents,
--ignore-file-name-case ignore case when comparing file names.
If you want to avoid warnings (mostly usefulness warnings) about differences in the
.DS_Store files, then use:
diff -rq directory1/ directory2/ | grep -v .DS_Store
The diff tool that comes with Bare Bones Software's Text Wrangler has directory comparison, although it only shows which files are in both directories, and which are only in each of the directories. When you select a file that's in both you can edit by merging changes line by line with the click of a button. It doesn't let you move files though. You have to do this externally (eg via Finder).
I find it to be one of the better free options.
Easiest solution: Sync the files using Dropbox or similar, then just use WinMerge on Windows.
The FileMerge utility that ships with Xcode doesn't compare folders and doesn't do merge/editing.
Another neat tool to achieve this is rsync, as described on Unix & Linux StackExchange. To compare two folders you can do
rsync -avun $SOURCE $TARGET
And if you are really concerned about file consistency / bit rot there is also the c option to compare file checksums
rsync -avnc $SOURCE $TARGET