If you change that to:
echo ${15}
It will work.

Also $_ will give you the last argument of previous command.

$ cat doit
#!/bin/bash
echo ${20}

$ ./doit a b c d e f g h i j k l m n o p q r s t u v w x y z;echo "$_"
t
z

#!/bin/bash

num="$#"
lastp=( echo $@ )

echo ${lastp[$num]}

Hi, /bin/bash.

Yes, ${15} worked on all the Bourne-related shells I found on (Debian) Linux: pdksh, dash, bash, bash-posix, zsh. It failed on sh/jsh on Solaris, but at least an error message was produced there.

I changed my demo script to include this illustration for future use.

Thanks ... cheers, makyo

Hi, ygloo.

Yes, that seemed to have worked even in my v2 bash. Inventive ... cheers, makyo

I just noticed nobody mentioned ${!#}. Guess what ${!#} is? Yep, it's the last command line argument.

$cat doit
#!/bin/bash
echo "No. of command line arguments = $#"
echo "Last command line argument = ${!#}"

$./doit 1 2 3 4 last
No. of command line arguments = 5
Last command line argument = last

Everyone seems to be using bash. I use zsh, in which parameters can be subscripted like python/etc.

i.e. the last argument is $argv[-1], or $@[-1], or $*[-1].