I would like to have a folder mounted as temporary, which is actually my RAM. This is so that, for example, I could copy a movie into my RAM, unplug my external drive, and then watch it. Can this be done? Thank you :)
Yes, it is possible. Follow this procedure.
To make the folder you want to mount the ram disk to:
Execute the following line to create a ram disk. The size can be whatever you like as long as it fits into your available memory.
mount -t tmpfs -o size=1024m tmpfs /mnt/ramdisk
If you want this to be permanent do the following steps:
Open this file in nano or in whatever your preferred editor is.
Add the following line to that file and save the file.
tmpfs /mnt/ramdisk tmpfs nodev,nosuid,noexec,nodiratime,size=1024M 0 0
This line is supposed to be one uninterrupted line. Again size can be whatever you see fit.
Now reboot and you will have a ram disk.