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Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.
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Assumed dir A, B, C are subdirs of the current dir
Exact syntax of the command is:
rsync -v -r --size-only --compare-dest=/path_to_A/A/ /path_to_B/B/ /path_to_C/C/
(do not omit end-slashes, since that would copy only the names and not the contents of subdirs of dir B to dir C)
You can replace --size-only with --checksum for more thorough file differences validation
-n, --dry-run perform a trial run with no changes made
Outputs the number of different pixels.
2 params to increase tolerance:
* thumbnails size
* fuzz, the color distance tolerance
See http://en.positon.org/post/Compare-/-diff-between-two-images for more details.
Compare the ls -Rl output of two directories in meld (you can also use diff -y instead of meld).
The normal output of 'diff' is a wonderful thing. But just sometimes, you want something that is a little more... well... readable.
This is that command.
-d - (optional) find the minimal set of changes
-b - (optional) ignore changes in the amount of whitespace
-B - (optional) ignore changes that just insert or delete blank lines
-y - this is where the magic happens! Use the side-by-side output format.
-w $COLUMNS - more magic! Instead of using 80 columns, use the current width of the terminal.
This commands will make it easier to select only common items between two files being compared. If your lines start with things other than lowercase a-z, adjust this Regex appropriately. Number of lines in the output has been set to no more than 10000, and should be adjusted as needed.