Bash Special Variables

$@

Represents all arguments that are passed in, and allows these arguments to be referenced by positional variables $1, $2...

main () {
  echo "\$1 is $1"
  echo "\$2 is $2"
  for el in $@
  do
    echo "loop"
  done
}

main $@

# When we run `./script.sh foo bar`:
# $1 is foo
# $2 is bar
# loop is printed 2 times, proof that there are a total of 2 args

How Multi-word Arguments are Handled

main () {
  echo "\$1 is $1"
  echo "\$2 is $2"
  for el in $@
  do
    echo "loop"
  done
}

main $@

# When we run `./script.sh "john smith" "anna nicole"`:
# $1 is john
# $2 is smith
# loop is printed 4 times, proof that there are a total of 4 args

main () {
  echo "\$1 is $1"
  echo "\$2 is $2"
}

main "$@"

# When we run `./script.sh "john smith" "anna nicole"`:
# $1 is john smith
# $2 is anna nicole
# loop is printed 2 times, proof that there are a total of 2 args

When $@ is wrapped in double-quotes, the space in "john smith" is preserved; otherwise, all spaces will serve as delimeter between arguments.