All kinds of dollar signs in shell

dollar-signs.sh

#!/bin/bash

# Run this script with dollar-sign.sh a b c

echo "process id =" $$

echo

echo "how many arguments = $#"

echo "arg0, 1, 2, 3 =" $0 $1 $2 $3

echo

echo "\$* =" $*

echo "\$@ =" $@

echo

echo "print each param from \$*"
for var in $*
do
    echo "$var"
done

echo "print each param from \@"
for var in $@
do
    echo "$var"
done

echo


# $* 與 $@ 的差異只有在 $* 被雙引號包住時看得出來
# "$*" 會把所有參數用空白隔開並且顯示在同一行
echo "print each param from \"\$*\""
for var in "$*"
do
    echo "$var"
done

echo "print each param from \"\@\""
for var in "$@"
do
    echo "$var"
done