glibc/rellns-sh

#! /bin/sh
# rellns-sh - Simplified ln program to generate relative symbolic link.
# Copyright (C) 1996 Free Software Foundation, Inc.
# Written by Ulrich Drepper <drepper@cygnus.com>, October 1996
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

if test $# -ne 2; then
  echo "Usage: rellns SOURCE DEST" >&2
  exit 1
fi

# We only handle the case where SOURCE is the name of an existing file
if test ! -f $1; then
  echo "rellns: $1 must name an existing file" >&2
  exit 1
fi

case $1 in
/*)
  # Make both paths absolute.
  to=`echo $1 | sed 's%^/%%'`

  if test -d $2; then
    from=`echo $2 | sed 's%/*$%%'`
  else
    from=`echo $2 | sed 's%/*[^/]*$%%'`
  fi

  case "$from" in
  /*) from=`echo $from | sed 's%^/*%%'` ;;
  ?*) from=`cd $from && pwd | sed 's%^/%%'` ;;
  *) from=`pwd | sed 's%^/%%'` ;;
  esac
  ;;
*)
  to=$1

  if test -d $2; then
    from=`echo $2 | sed 's%/*$%%'`
  else
    from=`echo $2 | sed 's%/*[^/]*$%%'`
  fi
  ;;
esac

while test -n "$to" && test -n "$from"; do
  preto=`echo $to | sed 's%^\([^/]*\)/.*%\1%'`
  prefrom=`echo $from | sed 's%^\([^/]*\)/.*%\1%'`

  test "$preto" != "$prefrom" && break

  to=`echo $to | sed 's%^[^/]*/*\(.*\)$%\1%'`
  from=`echo $from | sed 's%^[^/]*/*\(.*\)$%\1%'`
done

while test -n "$from"; do
  rfrom="../$rfrom"
  from=`echo $from | sed 's%^[^/]*/*%%'`
done

ln -s $rfrom$to $2