What is the best way to disable Caps Lock's normal behavior, and make it do something else?
# Caps Lock becomes an additional Ctrl.
setxkbmap -option caps:ctrl_modifier
Here's a command line displays both counters and strips away all other information the commands also output:
date; awk '/sda1/ {print $3"t"$10 / 2 / 1024}' /proc/diskstats; cat /sys/fs/ext4/sda1/lifetime_write_kbytes