Union, Intersection and Exclude with the FIND-command?

Question

I need to manage lists with find-command. Suppose the lists have random names in non-distinct lists (ie their intersection is not empty set). How can I do:

A \ B

find files in the list A except the files in the list B

A intersection B

find files common to the lists A and B

Please, consult here.

A union B

find all files in the two lists

EXAMPLES

$ find . | awk -F"/" '{ print $2 }'

.zcompdump
.zshrc
.bashrc
.emacs

$ find ~/bin/FilesDvorak/.* -maxdepth 0 | awk -F"/" '{ print $6 }'

.bashrc
.emacs
.gdbinit
.git

I want:

A \ B:

.zcompdump
.zshrc

A Intersection B:

.bashrc
.emacs

A Union B:

.zcompdump
.zshrc
.bashrc
.emacs
.bashrc
.emacs
.gdbinit
.git

A try for the Intersection

When I save the outputs to separate lists, I cannot understand why the command does not take the common things, ie the above intersection:

find -f all_files -and -f right_files .

Questions emerged from the question:

1. find ~/bin/FilesDvorak/.* -maxdepth 0 -and ~/.PAST_RC_files/.*

2. Please, consult for recursive find Click here!

3. find ~/bin/FilesDvorak/.* -maxdepth 0 -and list

Answer 1

Seriously, this is what comm(1) is for. I don't think the man page could be much clearer: http://linux.die.net/man/1/comm

Answer 2

There are several tools that can help you find the intersection in file lists. 'find' isn't one of them. Find is for finding files that match a certain criteria on the filesystem.

Here are some ways of finding your answer.

To generate your two file lists

find . -maxdepth 1 | sort > a
(cd ~/bin/FilesDvorak/; find . -maxdepth 1 | sort > b)

Now you have two files a and b that contain directory entries without recursing into sub directories. (To remove the leading ./ you can add a "sed -e 's/^.\///'" or your first awk command between the find an sort)

To find the Union

cat a b | sort -u

To find the A\B

comm -23 a b

To find the intersection

comm -12 a b

'man comm' and 'man find' for more information.