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Doing: diff -r -X <ignore-list> <src-dir> <dest-dir>

doesn't seem to make diff ignore entries in <ignore-list> if they are of the form <dir>/<file>.

Entries of the form <file> do however get considered. This is a problem since I might have multiple files named <file> in different sub-directories, some of which I don't want ignored.

There doesn't seem to be much information regarding pattern syntax in the manpage for diff either. From what I can tell, it's just the base-name of a file that is considered by diff (see http://forums.gentoo.org/viewtopic-t-889788-start-0.html if you're interested).

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1 Answer 1

up vote 10 down vote accepted

Listing directories should work; e.g., here's what I've used in a script (assuming gnu diff),

diff -r \
   --exclude="*~" \
   --exclude=".svn" \
   --exclude=".git" \
   --exclude="*.zip*" \
   --exclude="*.gz" \
   --exclude="*.tar" \

...which ignores contents of .svn and .git dirs, but also individual files named *.zip/*.gz/etc.

Edit: In order to filter paths of the form dir_a/file1 but still diff files with the same basename, such as dir_b/file1 or dir_a/b/file1, then a list of files to diff would have to be generated (for example, using find), and the file to compare derived from these paths; e.g., given

$ find ONE TWO -type f -print 

you generate the list of files to compare, excluding for example */a/2.txt but still comparing other files named 2.txt. Just "find" all files except ONE/a/2.txt (a regexp can also be used here, such as .*/a/2.txt)

$ find ONE -type f \( ! -regex 'ONE/a/2.txt' \) \
    -exec bash -c 'diff -q "${1}" "${2/ONE/TWO}"' - {} {} \;  

which in effect ignores ONE/a/2.txt (and TWO/a/2.txt), but still compares the other files named 2.txt:

diff -q ONE/a/1.txt TWO/a/1.txt
diff -q ONE/a/b/2.txt TWO/a/b/2.txt

Edit: Or, more fun with find (additional fun left as an exercise for the reader), select the files or directories to exclude and then diff everything else:

$ find ONE \( -regex 'ONE/a/2.txt' -o -name b  -prune \)  \
    -o -type f -exec bash -c 'echo diff -q "${1}" "${2/ONE/TWO}"' - {} {} \

The above example excludes the specific file "{top}/a/2.txt", any directory named "b", and everything else is diff'd. (Instead of simple "-name b" you could also use "-regex '.*/b'" - note, no trailing "/".)

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Thanks but I think you're missing the point. The only support there seems to be is when you use a 'base-name'. That could be the name of a directory or a file. In either case, diff ignores what you've asked for. The problem arises when you use paths. For example, I can't get diff to ignore /an/absolute/path/to/a/file or ./a/relative/path/to/a/file. –  Ash Sep 13 '13 at 6:52
diff --exclude="/this/specific/file/that/im/explicitly/pleading/you/to/ignore". It won't work. –  Ash Sep 13 '13 at 6:54
correct, exclude patterns are matched against the files' basename (as per gnu.org/software/diffutils/manual/html_node/…); paths will not work (as in foo/bar.txt). To do that, you will likely have to run find to generate the list of filenames, and derive the path to the file to compare. –  michael_n Sep 14 '13 at 11:17
updated answer to include example excluding file paths from the diff, instead of just using basename –  michael_n Sep 14 '13 at 11:46
Okay, I see what you're proposing but there appears to be a problem. I need to consider directories as well, not just files (i.e -type f). Now, while you can still prune out certain files using regexp with find, if the input to diff contains a directory, it will go through and compare files within that directory and some of these files might need to be ignored....so you're back to square 1. –  Ash Sep 16 '13 at 4:26

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