Shell Programming and Scripting

I have a folder like this

Code:

ls input1

dir1 dir2 dir3 file1 file2 file3

dir1, dir2 and dir3 are sub-folders inside the folder input1

Code:

ls input2

dir1 dir2 dir3 file1 file2 file3

My dir1 in input1 folder has files f1, f2, f3 and f4.

My dir1 in input2 folder has file f4 and f5.

Now, I would like to have a bash script which checks the sub-folder names and updates the contents, but never replaces the entire contents.

If I would like to copy the contents of input2 to input1, then my dir1 sub-folder's contents in input1 should be f1, f2,f3,f4 and f5. But not just f4 and f5.

I could try cp, but my folders size is more than 500GB.

Any helps are highly appreciated. Thanks

If you want input1 and input2 to always be the same, you could make input2 a symlink to input1.

If they must be kept separate for some reason and merged later -- if you're expecting bash to be faster than cp, that's kind of optimistic. Special-purpose utility optimized for this, vs a hand-written shell script?

Code:

cp -nr input2/* input1/

-n for no-clobber, it will not overwrite anything in input2.

Thanks Corona. I will try this.

I don't think 'cp -r' really cares, it just walks the input tree and writes the output tree. You could walk both trees and make a new tree. Just make sure the input dir(s) are what you want in (not as) the output dir. While 'cp -r' will create the target if it is missing, but next time it will put all the files one level lower on the tree, so if the first time it creates dir1 with file1, the next time it will create dir1/dir1 and file1 in that. Ditto for scp, rcp and sometimes mv.