For i in 1-100 do
Basically count to 100 and perform an operation each time i increases.
for ((i=1; i<=100;i++)) do echo $i done
for loop 1 liner
for ((i=1; i<=100;i++)) do echo $i ; done
While true (Execute forever)
Handy if you just want a script to run and repeat the same thing over and over again. Doesn't stop till you kill it.
while true do echo "Repeat till infinity" sleep 1 done
While command is true
The following will execute the loop as long as the command in the () returns true. Once it returns false, it'll stop the loop
while (fping incredigeek.com | grep alive); do echo alive sleep 1 done