How to change the default fold of the downloading sra data using prefetch ?

1, come to bin directory, such as: /home/sratoolkit.2.5.5-centos_linux64/bin 
2, run it in the terminal:    ./vdb-config -i
3, change the fold of Workspace Name to a big harddisk.
4, by the way, use Tab to move

References:
https://www.biostars.org/p/175096/