Macos – Diff between two directories and keep only the unchanged ones

bashdiff()macos

I need to diff two directories:

 A: /path1/
 B: /path2/

The directory A contains all files and subdirectories that are also contained in B.
The files in A (and in its subdirectories) can have different contents of the equivalent files in B.
The directory A (and its subdirectories) also has extra files that do not exist in B.

What I would like to achieve is:

Keep only the files in A that differ from the files in B plus all the extra files that don't exist in B.
Delete all the other files in A that do not respect the previous rule.

Best Answer

This approach should work:

cd /path1

find . -type f -exec cmp -s {} /path2/{} \; -delete

How it works:

find . -type f goes through all files in the current directory (A) and its subdirectories.
cmp -s {} /path2/{} silently (-s) compares the currently processed file ({}) to the matching file in B (/path2/{}).
If the files are identical, cmp returns true and the -exec condition matches.
If the -exec condition matches, -delete deletes the file.

I suggest replacing -delete with -print before running the actual command to verify if it works as expected.

To deal with leftover empty directories, you can execute the command:

find . -type d -exec rmdir -p {} \; 2> /dev/null

-type d only finds directories.
-exec rmdir -p {} \; executes rmdir -p {} for every directory that has been found.

{} is the directory that has been found, and the -p switch makes rmdir remove its empty parent directories as well.
2> /dev/null suppresses the error messages that will arise from trying to delete non-empty or previously deleted directories.

Since rmdir cannot delete non-empty directories, this should be the safest way.

Related Solutions

Macos – Does rsync delete files, folders at destination by default

By default, rsync does not delete files but that depends on the commands options you specify. You can use any the following if you WANT to delete files:

−−del (alias for −−delete−during)
−−delete (deletes extraneous files from dest dirs)
−−delete−before (receiver deletes before xfer [default])
−−delete−during (receiver deletes during xfer, not before)
−−delete−after (receiver deletes after xfer, not before)
−−delete−excluded (also delete excluded files from dest dirs)
−−max−delete=NUM (don’t delete more than NUM files)

Since you specifically called out the -a option, here's what the man page says

−a, −−archive >

This is equivalent to −rlptgoD. It is a quick way of saying you want recursion and want to preserve almost everything (with −H being a notable omission). The only exception to the above equivalence is when −−files−from is specified, in which case −r is not implied.

Note that −a does not preserve hardlinks, because finding multiply-linked files is expensive. You must separately specify −H.

So it seems the answer to your question is NO, it won't be deleted given your examples.
HTH

Linux – Recursively loop through directories and run a command on a file in the directory

I’m not 100% solid on how JAD works exactly, but based on the info I found in this README file, this find command should give you a start:

find . -type f -name '*.class' |\
  while IFS= read -r java_class_path
  do
    java_dirname=$(dirname "${java_class_path}")
    jad -sjava -d"${java_dirname}" "${java_class_path}"
  done

The -s option will set the output extension to .java and the -d sets a destination directory for file output based on where the original .class file was found via find. The key to solving problems like this is to understand you are not the first person who wanted to output command line output to another destination.

Best Answer

Related Solutions

Macos – Does rsync delete files, folders at destination by default

Linux – Recursively loop through directories and run a command on a file in the directory

Related Question