help with advanced file copying techniques

[solrac]

Is it possible to copy to multiple directories and ignore unchanged files?

Commandline is fine.

directory tree 1:
file1.txt
file2.txt

directory tree 2:
file1.txt (identical to file1.txt above)

directory tree 3:
{blank}

I want a one line copy command (hopefully) that will do the following:

copy ALL files from directory 1 to BOTH directory 2 and 3 simultaneously. (By simultaneously i mean with ONE command)

will NOT copy file1.txt to directory 2 because it is identical, so skip it. (Only copy "NEW" or "CHANGED" files)

Thanks!

[Natobasso]

Say you have two identical file folders, one a back up and one the original/worker. If you copy all contents from the original to the back up it will ask you if you want to replace all or just the older files in the back up directory.

Be careful of folders within folders as they need to be copied individually.

[MisterMe]

Is it possible to copy to multiple directories and ignore unchanged files?

...

You want backup software. For this, I use Qdea's Synchronize Pro X. It is shareware, but works without paying the fee. If you pay the fee, it works automatically. There are other backup utilities as good, but none are better.