Robocopy to copy missing files only

I need help with Robocopy parameters. I've used /mir before but this
time I only want to copy source files missing on destination. What
parameters do I need? I've used /l to test but the log doesn't look
like it would do the right thing.

You can use the basic command, robocopy will copy only files that are
different in the source folder than what is in the destination directory
Robocopy "sourcefile" "destination"
Then I like to use /R:2 /W:30 Which retries 2 times and sets the timeout to
30seconds. Good Luck!

If you use "/XO" that will do an incremental copy of only newer files
(i.e. eXclude Older files). That usually gets it done.

Robocopy by default shall only copy a file incase the source and destination have different time stamps or different file sizes. When a source file is edited to a newed or older date or time then robocopy would write it to the destination. You can try to get few sample files and test the behaviour before running the command agaisnt thousands of files.

Even I was facing the same issue and was searching for a solution that might work while specifying a drive or a directory. After searching I found out that I had to add a blank character before the leading double quote, like for example - the directory name for Robocopy = '\"' + directory name + ' "\'. So, after allowing blank characters in file names was a good idea I guess.