#!/bin/sh
#
# Scott Snyder's relpathto
#
# Usage: relpathto PATH
#
# Writes to stdout the relative path from the current directory to PATH.
# PATH may be either absolute or relative.  
#
# sss Feb, 1998.
#

# Get the target path.
targ=$1

if [ "$targ" = "" ]; then
  echo "Usage: $0 path" 1>&2
  exit 1
fi

# Make sure it's valid.
if [ ! -d $targ ]; then
  echo "$0: Invalid path \`$targ'." 1>&2
  exit 1
fi

# Get the current directory.
curdir=`/bin/pwd`

# And the target directory.
# Do it by changing to that directory and doing pwd.
# This ensures that we have an absolute path.
cd $targ
targdir=`/bin/pwd`
cd $curdir

# Handle the case where curdir and targdir are the same.
if [ "$curdir" = "$targdir" ] ; then
  echo "."
  exit 0
fi

# Pull matching pathname components off the heads of the paths.
curhead=`expr "$curdir" : '/\([^/]*\)'`
targhead=`expr "$targdir" : '/\([^/]*\)'`

while [ "$curhead" = "$targhead" ] ; do

  curdir=`expr "$curdir" : '/[^/]*\(/.*\)'`
  targdir=`expr "$targdir" : '/[^/]*\(/.*\)'`

  curhead=`expr "$curdir" : '/\([^/]*\)'`
  targhead=`expr "$targdir" : '/\([^/]*\)'`

done

# Strip off the leading slashes.
curdir=`expr "$curdir" : '/\(.*\)'`
targdir=`expr "$targdir" : '/\(.*\)'`

# Replace every remaining component in the current path with `..'.
uppath=`echo $curdir | sed -e 's@[^/][^/]*@..@g'`

# Tack on the remaining target path.
# Add a directory separator between them only if neither is blank.
reslt=$uppath

if [ "$reslt" != "" -a "$targdir" != "" ]; then
  reslt=$reslt/
fi

# Done.
echo $reslt$targdir