for var in item1 item2 item3; do echo $var; done

echo 1 + 1 will print 1 + 1. To (integer) evaluate use echo $((1 + 1)) or echo $[1 + 1].

For arbitrary precision pipe expression to bc -l, i.e.: echo 3/4 | bc -l.

• $0 is the name of the script.

• $n is the nth parameter.

• $# is the number of parameters (excluding $0)

• $@ is all parameters (remaining: see below).

Useful motif to have an “all remaining parameters” parameter (note that all single parameters take $1):

var1=$1
shift
var2=$1
shift
alltherest=$@

if [ $# -eq 0 ]
then
   echo $usage
   exit
fi

for var in item1 item2 item3
do
   echo $var
done

read varname
echo "varname: $varname"