ctrl u erases the current line
ctrl w erases the last word you tpyod
ctrl c kills a running process you just started from the command line (usually)
history <number> displays the last <number> of commands typed
EX:
history 15 displays the last 15 commands ,with a number
take that number and type !<number> to rerun the command
sample:
user:$ history 5
500 su
501 bnxd hjxrfyj
502 history 15
503 df
504 history 5
localhost:/~
user:$ !503
df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda3 19919988 19293256 626732 97% /
/dev/hda1 133191012 97840548 28584692 78% /home
/dev/sda1 219718816 179836836 28720824 87% /home/user/mnt/sdb
tmpfs 1035476 0 1035476 0% /dev/shm
/dev/sdb1 1981024 1981024 0 100% /media/disk-1
localhost:/~
user:$