iankelling.org Git - distro-setup/blob - path_add-function

   1 #!/bin/bash
   2 # Copyright (C) 2016 Ian Kelling
   3
   4 # Licensed under the Apache License, Version 2.0 (the "License");
   5 # you may not use this file except in compliance with the License.
   6 # You may obtain a copy of the License at
   7
   8 #     http://www.apache.org/licenses/LICENSE-2.0
   9
  10 # Unless required by applicable law or agreed to in writing, software
  11 # distributed under the License is distributed on an "AS IS" BASIS,
  12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 # See the License for the specific language governing permissions and
  14 # limitations under the License.
  15
  16
  17 # avoiding bashisms so it can be used in edge cases where I don't have bash,
  18 # however, I'm not super confident that I've avoided them all
  19 #
  20 path_add() {
  21     local help="usage: path_add [options] PATH
  22 --help:     print this
  23 --end:      adds to end of path, which will give it lowest priority
  24 --ifexists: add to path only if directory exists"
  25     local found x y ifexists end loop newpath
  26     ifexists=false
  27     end=false
  28     loop=true
  29     # portable substring matching is ugly http://mywiki.wooledge.org/BashFAQ/041
  30     while $loop; do
  31         case $1 in
  32             --*)
  33                 if [ "$1" = --end ]; then
  34                     end=true
  35                 elif [ "$1" = --ifexists ]; then
  36                     ifexists=true
  37                 elif [ "$1" = --help ]; then
  38                     echo "$help"
  39                     return
  40                 fi
  41                 shift
  42                 ;;
  43             *)
  44                 loop=false
  45                 ;;
  46         esac
  47     done
  48     IFS=:
  49     # build up the path without the components we want to add
  50     for y in $PATH; do
  51         for x in "$@"; do
  52             if [ "$x" = "$y" ]; then
  53                 found=true
  54             else
  55                 found=false
  56             fi
  57         done
  58         if ! $found; then
  59             if [ ! "$newpath" ]; then
  60                 newpath="$y"
  61             else
  62                 newpath="$newpath:$y"
  63             fi
  64         fi
  65     done
  66
  67     unset IFS
  68     PATH="$newpath"
  69     for x in "$@"; do
  70         if ! $ifexists || [ -d "$x" ]; then
  71             if [ ! "$PATH" ]; then
  72                 PATH="$x"
  73             elif $end; then
  74                 PATH="$PATH:$x"
  75             else
  76                 PATH="$x:$PATH"
  77             fi
  78         fi
  79     done
  80 }