The script is a busy loop: it keeps reading the GPIO pins over and over. It doesn't consume much memory but it keeps the CPU busy.
You should set the GPIO pin in edge mode. The WiringPi author is considering adding a
wait command to the
gpio utility but currently there is no way to react to an edge trigger from a shell script.
A Python solution
There is a Python library for GPIO access, which supports edge mode. Here's some completely untested Python code that should do what you want.
from RPi import GPIO
Additional shell tips
(true) could be written just
true. The parentheses create a subprocess, which is completely unnecessary.
`gpio read 0` should be in double quotes. Without quotes, the output of the command is treated as a list of file name wildcard patterns. With double quotes, the output of the command is treated as a string. Always put double quotes around command substitutions and variable substitutions:
"$some_variable". Also, you should use the syntax
$(…) rather than
`…`: it has exactly the same meaning, but the backquote syntax has some parsing quirks when the command is complex. Thus:
if [ "$(gpio read 0)" -eq 1 ]
Don't put the root password in the script. If the script is running as root, you don't need sudo at all. If the script isn't running as root, then give the user running the script the permission to run
sudo reboot without supplying a password. Run
visudo and add the following line:
userwhorunsthescript ALL = (root) NOPASSWD: /sbin/reboot ""
Note that if there's an entry for the same user in the sudoers file that requires a password, the
NOPASSWD entry must come after.
Once you trigger a reboot, you don't need to break the loop, the system will stop anyway.
If you decide to keep using this shell script, here's an improved version which only checks the button state every second. Note that since the pin is only read once per second, this means you need to keep the button pressed for at least one second to be sure that the event is picked up.
gpio mode 0 in
while sleep 1; do
if [ "$(gpio read 0)" -eq 1 ]; then