How can a bash (or sh) script reliably get a path to itself? (one-liner)

oneliner.sh

#!/bin/sh

# reliable path to current script in one-liner (handles spaces)
scriptpath=$(l=$(which "$0"); while :; do cd "$(dirname "$l")"; p=$(basename "$l"); \
    l=$(readlink "$p") || break; done; echo $(pwd)/$p)

echo \'$scriptpath\'

resolve-links.sh

#!/bin/sh

# this function resolves links recursively, leaving you with
# a direct path to a real file.  Handles spaces in paths correctly.
# if the file doesn't actually exist, strange things will happen.
function reslinks {
  (link=$1;
    while : ; do cd "$(dirname "$link")"; path=$(basename "$link"); link=$(readlink "$path") || break; done
    echo $(pwd)/$path)
}

# use the reslinks function get a reliable path to this script
# (the `which $0` is only needed on platforms where $0 doesn't 
#  include the full path to scripts that were invoked via $PATH)
#
scriptpath=$(reslinks "$(which "$0")")

echo \'$scriptpath\'

updated to support links to absolute paths, and also chains of multiple links.

Improved (and shortened) the code a little. Added the example with a general purpose reslinks function. Added support for paths that include spaces.