TFTP

When using Busybox TFTP client

get file:
tftp -g -r filename.txt tftpserverip_or_hostname

put file:
tftp -p -l filename.txt tftpserverip_or_hostname

Getting a file not found error? It seems that the file must exist on the server first, so if you want to upload a new file, first go to the server via SSH or something and create a dummy file of the same name.

Getting permission denied error? You don't have enough permissions on the dummy file you are trying to upload over. SSH to the TFTP server and chmod 777 the file. Upload it. Then change the permissions back to 644 or something.

When using OSX
get file, launch Terminal and type these commands:
tftp
binary
connect tftpserverip_or_hostname
get filename.txt

put file, launch Terminal and type these commands:
tftp
binary
connect tftpserverip_or_hostname
put filename.txt