rafael@rafael-linuxer:/media$ sudo mkfs /dev/sdb
mke2fs 1.40.2 (12-Jul-2007)
/dev/sdb is entire device, not just one partition!
Proceed anyway? (y,n) y
/dev/sdb is mounted; will not make a filesystem here!

rafael@rafael-linuxer:/media$ sudo mkfs /dev/sdb1
mke2fs 1.40.2 (12-Jul-2007)
Could not stat /dev/sdb1 --- No such file or directory

rafael@rafael-linuxer:/media$ sudo mkfs /dev/sdb0
mke2fs 1.40.2 (12-Jul-2007)
Could not stat /dev/sdb0 --- No such file or directory

rafael@rafael-linuxer:/media$ sudo mkfs /dev/sdb2
mke2fs 1.40.2 (12-Jul-2007)
Could not stat /dev/sdb2 --- No such file or directory