iankelling.org Git - lnf/blob - lnf

   1 #!/bin/bash
   2 # Copyright (C) 2014-2016 Ian Kelling
   3 # This program is under GPL v. 3 or later, see <http://www.gnu.org/licenses/>
   4
   5 _lnf_existing_link() {
   6     local target dest_file dest_dir
   7     target="$1"
   8     dest_file="$2"
   9     dest_dir="$3"
  10     if [[ -L $dest_file ]]; then
  11         if [[ $(readlink $dest_file) == "$target" ]]; then
  12             # Leave the link in place, but make sure it's
  13             # ownership is right.
  14             # already exists. links all get 777 perms, so
  15             # we dun have to mess with that.
  16             if [[ $(stat -L -c%a "$dest_dir") == 2* ]]; then
  17                 grp=$(stat -L -c%g "$dest_dir")
  18             else
  19                 grp=$(id -g)
  20             fi
  21             if [[ $EUID == 0 && $(stat -c%u "$dest_file") != 0 ]]; then
  22                 chown 0:$grp "$dest_file"
  23             elif [[ $(stat -c%g "$dest_file") != "$grp" ]]; then
  24                 chgrp $grp "$dest_file"
  25             fi
  26             return 1
  27         fi
  28         to_remove+=("$dest_file")
  29     elif [[ -e $dest_file ]]; then
  30         to_remove+=("$dest_file")
  31     fi
  32     to_link+=("$target")
  33 }
  34 lnf() {
  35     local help="Usage:
  36        lnf [OPTIONS] -T TARGET LINK_NAME     (1st form)
  37        lnf [OPTIONS] TARGET                  (2nd form)
  38        lnf [OPTIONS] TARGET... DIRECTORY     (3rd form)
  39 Create symlinks forcefully
  40
  41 If the link already exists, make it's ownership be the same as if it was
  42 newly created (only chown if we are root).  Removes existing files using
  43 trash-put or rm -rf if it is not available, or if trash-put fails due to a
  44 limitation such as a cross-filesystem link. Create directory of link if
  45 needed. Slightly more restrictive arguments than ln.
  46
  47 In the 1st form, create a link to TARGET with the name LINK_NAME.  In the 2nd
  48 form, create a link to TARGET in the current directory.  In the 3rd form, create
  49 links to each TARGET in DIRECTORY.
  50
  51 -n|--dry-run     Do verbose dry run.
  52 -v|--verbose     Print commands which modify the filesystem.
  53 -h|--help        Print help and exit.
  54 "
  55
  56
  57     local temp
  58     local verbose=false
  59     local dry_run=false
  60     local nodir
  61     temp=$(getopt -l help,dry-run,verbose hnTv "$@") || usage 1
  62     eval set -- "$temp"
  63     while true; do
  64         case $1 in
  65             -n|--dry-run) dry_run=true; verbose=true; shift ;;
  66             -T) nodir=-T; shift ;;
  67             -v|--verbose) verbose=true; shift ;;
  68             -h|--help) echo "$help"; return 0 ;;
  69             --) shift; break ;;
  70             *) echo "$0: Internal error! unexpected args: $*" ; exit 1 ;;
  71         esac
  72     done
  73
  74     if (( $# == 0 )); then
  75         echo "$help"
  76         return 1
  77     fi
  78
  79     if [[ $nodir ]]; then
  80         if (( $# != 2 )); then
  81             echo "lnf: error: expected 2 arguments with -T flag. Got $#"
  82             return 1
  83         fi
  84     fi
  85
  86     local reset_extglob=false
  87     ! shopt extglob >/dev/null && reset_extglob=true
  88     shopt -s extglob
  89
  90
  91     local -a to_remove to_link
  92     local x ret prefix dest_dir grp target
  93     local mkdir=false
  94
  95     if [[ $nodir ]]; then
  96         dest_file="$2"
  97         dest_dir="$(dirname "$dest_file")"
  98         _lnf_existing_link "$1" "$dest_file" "$dest_dir" || return 0
  99         if [[ ! -d $dest_dir ]]; then
 100             mkdir=true
 101             if [[ -e $dest_dir || -L $dest_dir ]]; then
 102                 to_remove+=("$dest_dir")
 103             fi
 104         fi
 105         to_link+=("$dest_file")
 106     elif (( $# >= 2 )); then
 107         dest_dir="${!#}"
 108         if [[ -d $dest_dir ]]; then
 109             prefix="$dest_dir" # last arg
 110             for target in "${@:1:$(( $# - 1 ))}"; do # all but last arg
 111                 # Remove 1 or more trailing slashes, using.
 112                 dest_file="${target%%+(/)}"
 113                 # remove any leading directory components, add prefix
 114                 dest_file="$prefix/${target##*/}"
 115                 _lnf_existing_link "$target" "$dest_file" "$dest_dir"
 116             done
 117         else
 118             to_link+=("${@:1:$(( $# - 1 ))}")
 119             mkdir=true
 120         fi
 121         if (( ${#to_link[@]} == 0 )); then
 122             return 0
 123         fi
 124         to_link+=("$dest_dir")
 125     elif  [[ $# -eq 1 ]]; then
 126         dest_file="${1##*/}"
 127         _lnf_existing_link "$1" "$dest_file" . || return 0
 128     fi
 129     if (( ${#to_remove[@]} >= 1 )); then
 130         if type -P trash-put >/dev/null; then
 131             if $verbose; then
 132                 echo "lnf: trash-put -- ${to_remove[*]}"
 133             fi
 134             if ! $dry_run; then
 135                 trash-put -- "${to_remove[@]}" || ret=$?
 136             fi
 137             # trash-put will fail to trash a link that goes across filesystems (72),
 138             # and for empty files (74)
 139             # so revert to rm -rf in that case
 140             if [[ $ret == 72 ]]; then
 141                 echo "lnf: using rm -rf to overcome cross filesystem trash-put limitation"
 142                 rm -rf -- "${to_remove[@]}"
 143             elif [[ $ret == 74 ]]; then
 144                 echo "lnf: using rm -rf to overcome empty file & hardlink trash-put limitation"
 145                 rm -rf -- "${to_remove[@]}"
 146             elif [[ $ret && $ret != 0 ]]; then
 147                 return $x
 148             fi
 149         else
 150             if $verbose; then
 151                 echo "lnf: rm -rf -- ${to_remove[*]}"
 152             fi
 153             if ! $dry_run; then
 154                 rm -rf -- "${to_remove[@]}"
 155             fi
 156         fi
 157     fi
 158
 159     $reset_extglob && shopt -u extglob
 160
 161     if $mkdir; then
 162         if $verbose; then
 163             echo "lnf: mkdir -p $dest_dir"
 164         fi
 165
 166         if ! $dry_run && ! mkdir -p "$dest_dir"; then
 167             echo "lnf error: failed to make directory $dest_dir"
 168             return 1
 169         fi
 170     fi
 171
 172     if $verbose; then
 173         echo "lnf: ln -s $nodir -- ${to_link[*]}"
 174     fi
 175     if ! $dry_run; then
 176         ln -s $nodir -- "${to_link[@]}"
 177     fi
 178 }
 179 lnf "$@"