Shell Programming and Scripting

way1:
$ for ((i=1;i<=100;i++)); do echo $i; done

way2:
$ for i in `seq 1 100`; do echo $i; done

While loop: 

$ i=1
while [ $i -le 100 ]
do
echo $i
((i+=1)) #or i=`expr $i + 1`
done

Until loop: 

$ i=1
until [ $i -eq 101 ]
do 
echo $i
((i+=1))
done

for ((i=1;i<=100;i++)) is one more for loop syntax in bash

i=1; while [[ $i -le 100 ]]; do echo $i; let i=i+1; done