Disks and filesystems

badblocks -v- s /dev/sdb >badblocks.log

Check a device for bad blocks

fdisk /dev/sdb

Manage disk partitions

df -h

Show filesystem block usage in human friendly format

df -i

Show filesystem inode usage

ls -i <file>

Show inode of <file>

rm -i <file>

Remove a file by its inode

mount -t <fstype> -o <options> <devicefile> <mountpoint>

Mount a filesystem (fstype and options can be omitted often)

mount -o loop /path/to/my-iso-image.iso /mnt/iso

Mount an .iso file

Performance

The graphical utility Disks has a benchmark option.

dd if=/dev/zero of=/dev/sdb bs=8k count=10k

Test disk write speed if no filesystems exists

dd if=/dev/zero of=/tmp/output bs=8k count=10k; rm -f /tmp/output

Test disk write speed on existing filesystems

Misc

/dev/null

The unix black hole. Write always succeeds with no effect at all.

/dev/zero

Provides an unlimited amount of null characters (ASCII 0). Can be used for cleaning disks or benchmarking (see #Performance)

Writing to /dev/zero is the same as writing to /dev/null