sd -- a drop-in replacement for `cd'

#!/usr/bin/env bash
#
#name: sdcmd
#depends: sd.ksh
#
#for use with tcsh alias defined as  "alias cd 'eval `sdcmd \!*`'".
#if called from `tcsh', quote `=num'-type arguments to prevent interpretation
#as a tcsh dirstack entry (i.e. use `\=num').

sdlines=512
sdmax=8192
[[ . sd.ksh ]] || exit 1
if [[ $? != 0 ]]; then
   #something is wrong. we try to do simple cd and exit this script.
   if [[ -d "$*" ]] || [[ "$*" == "" ]] || [[ "$*" == "-" ]]; then
      echo chdir $*
   else
      echo "echo $*: no such directory."
   fi
   return   #important...
fi

#we want this script to behave as closely as possible as the tcsh builtin
#`cd' does since it's probably aliased to that command as shown above.
#therfore, we go to the trouble to parse command line args.
#we simply ignore them, though.

opt=""
while getopts plvn var; do
   if   [[ "$var" == p ]]; then
      opt="${opt} -p"
      echo "${0##*/}: option -p ignored" >&2 
   elif [[ "$var" == l ]]; then
      opt="${opt} -l"
      echo "${0##*/}: option -l ignored" >&2
   elif [[ "$var" == n ]]; then
      opt="${opt} -n"
      echo "${0##*/}: option -n ignored" >&2
   elif [[ "$var" == v ]]; then
      opt="${opt} -v"
      echo "${0##*/}: option -v ignored" >&2
   fi
done
shift $((OPTIND - 1))

#always execute `sd' to enforce update of $dirv and suppress
#any messages (either errors or from `cd -'), since the present 
#script must output only the intended `cd command').
#do this in a subshell in order to prevent actual cd action!
#
(sd "$*" > /dev/null 2> /dev/null; sdlogappend)

#look up the name (a second time since we don't get it out of
#the previous `sd' call...)
#
dname=$(sdname "$*")
dname=${dname/%$'\n'*}

#note that we use `chdir' instead of `cd' in order to prevent
#recursion when defining the tcsh alias for `cd'.
#tcsh crashes during eval if the `cd' is not successful, so we test again.
if [[ -d "$dname" ]]; then
   echo "chdir \"$dname\""
elif [[ $dname == "-" ]]; then 
   echo chdir $dname
else
   echo "echo $dname: no such directory."
fi