i3status is a small program (about 1500 SLOC) for generating a status bar for
i3bar, dzen2, xmobar or similar programs. It is designed to be very efficient
by issuing a very small number of system calls, as one generally wants to
update such a status line every second. This ensures that even under high load,
your status bar is updated correctly. Also, it saves a bit of energy by not
hogging your CPU as much as spawning the corresponding amount of shell commands
would.