utils-dev/relative.sh

   1 #!/bin/sh
   2 # ---------------------------------------------------------------------------
   3 # Multi-Phasic Applications: SquirrelJME
   4 #     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
   5 #     Copyright (C) Multi-Phasic Applications <multiphasicapps.net>
   6 # ---------------------------------------------------------------------------
   7 # SquirrelJME is under the GNU General Public License v3+, or later.
   8 # See license.mkd for licensing and copyright information.
   9 # ---------------------------------------------------------------------------
  10 # DESCRIPTION: Calculates the relative path from one target to another
  11
  12 # Force C locale
  13 export LC_ALL=C
  14
  15 # Directory of this script
  16 __exedir="$(dirname -- "$0")"
  17
  18 # No base specified, just a target
  19 if [ "$#" -eq "1" ]
  20 then
  21         __base="$(pwd)"
  22         __targ="$1"
  23
  24 # Base and target specified
  25 elif [ "$#" -gt "1" ]
  26 then
  27         __base="$1"
  28         __targ="$2"
  29
  30 # Bad command call
  31 else
  32         echo "Usage: $0 [target]" 1>&2
  33         echo "       $0 [base] [target]" 1>&2
  34         exit 1
  35 fi
  36
  37 # Make absolute
  38 __base="$("$__exedir/absolute.sh" "$__base")"
  39 __targ="$("$__exedir/absolute.sh" "$__targ")"
  40
  41 # Keep going up to skip the parts of the path which are exactly the same
  42 __i=2
  43 while true
  44 do
  45         # Extract both components
  46         __a="$(echo "$__base" | cut -d '/' -f "$__i")"
  47         __b="$(echo "$__targ" | cut -d '/' -f "$__i")"
  48
  49         if [ "$__a" != "$__b" ]
  50         then
  51                 break
  52         fi
  53
  54         __i="$(($__i + 1))"
  55 done
  56
  57 # Go up the base directory and make dots for every path element
  58 __j="$__i"
  59 while true
  60 do
  61         __a="$(echo "$__base" | cut -d '/' -f "$__j")"
  62         __j="$(($__j + 1))"
  63
  64         # Nothing left to add
  65         if [ -z "$__a" ]
  66         then
  67                 break;
  68         fi
  69
  70         # Add slash
  71         printf '%s' "../"
  72 done
  73
  74 # Append elements on the second set from the base to the result
  75 __j="$__i"
  76 while true
  77 do
  78         __b="$(echo "$__targ" | cut -d '/' -f "$__j")"
  79         __j="$(($__j + 1))"
  80
  81         # Nothing left to add
  82         if [ -z "$__b" ]
  83         then
  84                 break
  85         fi
  86
  87         # Add that element
  88         printf '%s' "$__b"
  89
  90         # If this is not the last element, add the slash
  91         __zb="$(echo "$__targ" | cut -d '/' -f "$__j")"
  92         if ! [ -z "$__zb" ]
  93         then
  94                 printf '%s' "/"
  95         fi
  96 done
  97
  98 # Ending newline
  99 echo
 100