Finding myself to google about this everytime.

https://xkcd.com/1168/

1. Copy file using SSH

# download
$ scp user@server.address:/path/to/input/file /path/to/output/folder
# upload
$ scp /path/to/input/file user@server.address:/path/to/output/folder

2. Copy file to/from Docker

# download
$ docker cp dockerhostname:/path/to/input/file /path/to/output/file
# upload
$ docker cp /path/to/input/file dockerhostname:/path/to/output/file