I'm trying to initiate a file transfer from one computer to another. I have access to both but am using a 3rd computer. I'd rather not transfer the file to myself and then upload it. Is there a way I can initiate a file transfer from computer 1 to computer 2 from computer 3? I thought about using sftp but the path I need to get to (OSX box) is /Shared Items/Public and sftp doesn't seem to like the space. I've even tried cd /Shared\ Items/ but that didn't fly either. Any suggestions?

Not tried this, but it may well work:

From PC3, log in remotely to PC1 or PC2 using SSH (ssh <user>@<ip address>). This will give you access to the command line on one of the other PCs, from where you can launch sftp to connect to the other PC.

File or directory names with spaces in them can be accessed by enclosing the name in inverted commers - i.e. "Shared files" - although this does not work as part of a file path, so instead of typing cd gerald/"Shared files" you would need to use two cd commands. Where I can, I'm gradually changing filenames to remove the spaces.

Hope this helps,
Rob.