Script arguments

Count arguments

$ bash test.sh
0
$ bash test.sh abc def
2

To avoid making an executing a script, for testing purposes you can use set to force setting the arguments for the current subshell environment.

set -- apple banana "kiwi fruit"

The first is always the shell and not included in the count.

echo $0
# /bin/bash

echo $1
# apple
echo $2
# banana
echo $3
# kiwi fruit
echo $4
#

Use curly braces and quotes if you need double digits:

set -- a b c d e f g h i j k l m
echo "${11}"
# k
echo "$11"
# a1

echo "$@"
# apple banana kiwi fruit
echo "$*"
# apple banana kiwi fruit

The difference matters more in a for loop.

Quoted

@ - treated as multiple items and any items with spaces in them are kept as a single item.

  for X in "$@"; 
    do echo "- $X"; 
  done
  # - apple
  # - banana
  # - kiwi fruit

* - treated as a one item.

  for X in "$*"; 
    do echo "- $X"; 
  done
  # - apple banana kiwi fruit

Unquoted

@ and * give the same result here. Newlines and spaces separate data into items, constrast with quoted above.

  for X in $@; 
    do echo "- $X"
  done
  # - apple
  # - banana
  # - kiwi
  # - fruit