Reload current shell in place (useful for cleanly applying recent shell config updates)
exec $SHELL
Clear the current screen of text
clear
Time current command execution and output user and system timing information
time <command>
Prevent computer from sleeping and declare user as active
caffeinate -u -t <seconds>
Other caffeinate options
-d
Prevent display sleep-i
Prevent system idle sleep-m
Prevent disk idle sleep
Generate MD5 hash from file
md5 <file>
Generate SHA1 hash from file
shasum <file>
General maths interpreter (allows general equations entered into command line)
bc
Calculate result of math query using bc
echo <calculation> | bc
echo '5 * 8' | bc