iankelling.org Git - tee-unique/blob - appendu-function

   1 #!/bin/bash
   2 # Copyright (C) 2014 Ian Kelling
   3 # This program is under GPL v. 3 or later, see <http://www.gnu.org/licenses/>
   4
   5 appendu() {
   6     local help="Usage: appendu [OPTION]... FILE [LINE_SET]...
   7
   8 Append unique.
   9
  10 A LINE_SET is one or more lines. Append LINE_SET to FILE if it does not exist in
  11 FILE.  If no LINE_SET argument is given, read lines from stdin, and treat each
  12 as a single LINE_SET. Appended text is output to the terminal.
  13
  14   -s      don't try to use sudo when it would help us read or write the file
  15   --      stop processing arguments
  16   --help  display this message"
  17
  18     local readsudo writesudo x strings string content
  19     local dosudo=true
  20
  21     while true; do
  22         if [[ $1 == --help ]]; then
  23             echo "$help"
  24             return
  25         elif [[ $1 == -s ]]; then
  26             dosudo=false
  27             shift
  28         elif [[ $1 == -- ]]; then
  29             shift
  30             break
  31         else
  32             break
  33         fi
  34     done
  35
  36     if [[ ${#@} == 0 ]]; then
  37         echo "error: need 1 or more arguments"
  38         echo "$help"
  39         return 1
  40     fi
  41
  42     local file="$1"
  43     shift
  44
  45     local file_exists=false
  46     if [[ -e $file ]]; then
  47         file_exists=true
  48         [[ -r $file ]] || readsudo=sudo
  49         [[ -w $file ]] || writesudo=sudo
  50     else
  51         local dir="$(dirname "$file")"
  52         if [[ -d $dir ]]; then
  53             [[ ! -w $dir ]] && writesudo=sudo
  54         else
  55             echo "appendu error: $dir does not exist"
  56             return 1
  57         fi
  58     fi
  59     if ! $dosudo; then
  60         readsudo=
  61         writesudo=
  62     fi
  63
  64     if (( $# == 0 )); then
  65         unset IFS
  66         while read -r x; do
  67             strings+=( "$x" )
  68         done
  69     else
  70         strings=( "$@" )
  71     fi
  72
  73     if $file_exists; then
  74         # fix files with no newline at the end.
  75         # the following command won't work right on them.
  76         # e = run script, $a\ means append following text, but there is none,
  77         # so sed only does what it always does when it was supposed to modify a file,
  78         # which is append a newline if there was none.
  79         sed -ie '$a\' "$file"
  80         # command substitution removes any trailing newlines, so we have to add
  81         # a non-newline ending, we randomly chose "b", then remove it.
  82         content=$($readsudo cat "$file"; echo b) content=${content%b}
  83
  84         # we aren't using regex because we want to match strings,
  85         # but we also want our match to start at the beginning of a line,
  86         # or the beginning of the file, and to end at a line ending.
  87         # So we do some slick bash to match this.
  88         local start="?(*
  89 )"
  90         local end="
  91 *"
  92         for string in "${strings[@]}"; do
  93             [[ $content != $start"$string"$end ]] && $writesudo tee -a "$file"<<<"$string"
  94         done
  95     else
  96         for string in "${strings[@]}"; do
  97             $writesudo tee -a "$file"<<<"${strings[@]}"
  98         done
  99     fi
 100     return 0
 101 }