Re: [Help-bash] The best way to get the last element of $@

[John Kearney]

another option might be
  ks_GetElement(){
    local cnt=$1
    unset ReturnValue
    [ $cnt -ge 0 ] || cnt=$(($#+$cnt))
    while shift && [ $# -gt 0 ] ; do
      [ $((cnt-=1)) -eq 0 ] || continue
      break;
    done
    ReturnValue=${1:-<unset>}
    echo "ReturnValue=${ReturnValue}"
  }

  set -- arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8 arg9 arg10
  ks_GetElement 1 "$@"
  ks_GetElement -1 "$@"
  ks_GetElement 5 "$@"
  ks_GetElement -5 "$@"
  ks_GetElement 11 "$@"

gives you this
ReturnValue=arg1
ReturnValue=arg10
ReturnValue=arg5
ReturnValue=arg6
ReturnValue=<unset>


On Sat, Mar 21, 2015 at 12:22 AM, Dan Douglas <address@hidden> wrote:

> On Fri, Mar 20, 2015 at 5:25 PM, Dan Douglas <address@hidden> wrote:
> > Greg's way is fine but inefficient and non-portable.
>
> Actually the first way is quite portable (unless you use a bad shell
> that lacks local). String subscripting a bit less so, especially for `@'.
>
> Also of course I screwed up my quoting copying from an interactive
> shell...
>
>     #!/usr/bin/env bash
>
>     set foo bar
>
>     if ! ${BASH_VERSION+false}; then
>         # this only works in bash, but is still more portable than printf
> -v
>         last=${!#}
>     elif ! ${KSH_VERSION+false}; then
>         if [[ ${!KSH_VERSION} == .sh.version ]]; then
>             # Almighty hack to peek at caller's parameters.
>             function last.get {
>                 trap 'trap - DEBUG; ((.sh.level--)); eval
> ".sh.value=\$${#}\${ let .sh.level++; }"' DEBUG
>                 :
>             }
>         else
>             # mksh makes the obvious thing that SHOULD work everywhere
> actually
>             # work. Sadly, it can't dereference `#' a second time so
> it's still not
>             # dynamic.
>             nameref last=$#
>         fi
>     else
>         # For random shells.
>         eval last=\$$#
>     fi
>
>     # set -ft last.get
>     echo "$last"
>
> --
> Dan Douglas
>
>