Acho que fdisk ou df deve fazer por você.
$ sudo fdisk -l
Disk /dev/sda: 128.0 GB, 128035676160 bytes
255 heads, 63 sectors/track, 15566 cylinders, total 250069680 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x76e7062a
Device Boot Start End Blocks Id System
/dev/sda1 2048 70383615 35190784 7 HPFS/NTFS/exFAT
/dev/sda2 * 249434112 250048511 307200 7 HPFS/NTFS/exFAT
/dev/sda3 70385662 249432063 89523201 5 Extended
/dev/sda5 70385664 71383039 498688 83 Linux
/dev/sda6 71385088 73383935 999424 82 Linux swap / Solaris
/dev/sda7 73385984 249432063 88023040 83 Linux
$ df -h #working on Debian
Filesystem Size Used Avail Use% Mounted on
/dev/sda7 84G 75G 5.6G 94% /
udev 1.9G 4.0K 1.9G 1% /dev
tmpfs 768M 944K 767M 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 1.9G 364K 1.9G 1% /run/shm
/dev/sda5 484M 47M 413M 11% /boot