## resolve_path - recursively resolve path with sym links
## Type "FPATH=/path/to/resolve_path; resolve_path help=y" for man page.

function resolve_path {
  typeset OPATH=$PATH HELP SHOW VERBOSE ##
  typeset PATH i ipath
  typeset -u _I

  for i; do
    if [[ $i == *=* ]]; then
     _I=$i; eval $_I
    else
      ipath=$i
    fi
  done

# SKIP_B
  [[ $HELP == Y || $SHOW == Y ]] && {
    typeset -x PATH=$OPATH
    typeset me=resolve_path  # $0 in ksh93; not available for showme().

    function showme {
      typeset fp=$1
      typeset me=$2
      typeset i
      for i in $(IFS=:; print "$fp"); do
        [[ -r $i/$me ]] && cat $i/$me && break
      done 
    }
  
    [[ $HELP == Y ]] && {
      typeset tempfile=/tmp/$me.$$.$RANDOM
      rm -f $tempfile
      trap "rm -f $tempfile" EXIT INT
  
      showme $FPATH $me | sed -n "/^##/s:^## \{0,1\}::p" > $tempfile
      perldoc $tempfile
    }
  
    [[ $SHOW == Y ]] && {
      showme $FPATH $me | sed "/^# SKIP_B/,/^# SKIP_E/d; /^##/d; /##$/d"
    }
    return 0
  }
# SKIP_E
  typeset j PERL
  for j in /usr/bin/perl /bin/perl /usr/local/bin/perl; do
    [[ -x $j ]] && PERL=$j && break
  done

  typeset d f s="set"
  [[ $VERBOSE == Y ]] && print "$ipath"

  while [[ -n "$s" ]]; do
    j=${ipath%/*}
    [[ -z $j ]] && j=/
    d=$(cd $j >/dev/null && pwd -P)
    f=${ipath##*/}
    s=$($PERL -e "print(STDOUT readlink(\"$ipath\"));")
    if [[ -n "$s" ]]; then
      if [[ $s == /* ]]; then
        ipath=$s
      else
        ipath=$d/$s
      fi
      [[ $VERBOSE == Y ]] && print "$ipath"
    else
      ipath=$d/$f && print "$ipath"
    fi
  done
}
## =head1 NAME
## 
## resolve_path - recursively resolve path with sym links
## 
## =head1 SYNOPSIS
## 
##   FPATH=/path/to/resolve_path
##   resolve_path symlink [verbose=y] [help=y] [show=y]
## 
## =head1 DESCRIPTION
## 
## B<resolve_path> takes the path with sym links,
## write out the converted fully resolved path to stdout.
##
## If "help=y" is part of the arguments, the man page is shown. If
## the arguments include "show=y", then the function itself is displayed,
## which can be statistically included in other programs. If "verbose=y"
## option is used, the steps in resolving the path is shown.
## 
## =head1 EXAMPLE
## 
##   $ resolve_path /tmp/system
##   /tmp/export/redirect/ora02/system
##
##   $ resolve_path /tmp/system verbose=y
##   /tmp/system
##   /tmp/export/ora01/system
##   /tmp/export/redirect/ora01/../ora02/system
##   /tmp/export/redirect/ora02/system
## 
## =head1 SEE ALSO
## 
## ls(1), Perl readlink().
## 
## =head1 AUTHORS
## 
## Michael Wang <F<xw73@columbia.edu>>.
## 
## This is free software. You may copy or redistribute it under the same
## terms as Perl. 
## 
## If you modify it, you are required to send a copy of the modification to
## me via email.