i would like to sort a single line input with a script
input=$( echo "$@" | sort -ngr )
echo $input
but it not work

First of all Guy, if you want to nest commands in the middle of other commands, the nested commands need to be delimited with backward quotes, such as:

echo I am `whoami`, logged into `uname -n`

Secondly, sort command is for sorting multiple lines, not for sorting words on a single line. One approach is to pipe these words into awk to output each word on separate lines, which can then be sorted:

input=`echo $@ |
awk '{for(w=1;w<=NF;w++)print $w}' |
sort`
echo $input

And $input ends up as a single line because the newline characters get stripped.

James