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
  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 readsudo=false
  46     local file_exists=false
  47     if [[ -e $file ]]; then
  48         file_exists=true
  49         [[ -r $file ]] || readsudo=true
  50         [[ -w $file ]] || writesudo=sudo
  51     else
  52         local dir="$(dirname "$file")"
  53         if [[ -d $dir ]]; then
  54             [[ ! -w $dir ]] && writesudo=sudo
  55         else
  56             echo "appendu error: $dir does not exist"
  57             return 1
  58         fi
  59     fi
  60     if ! $dosudo; then
  61         readsudo=
  62         writesudo=
  63     fi
  64
  65     if (( $# == 0 )); then
  66         unset IFS
  67         while read -r x; do
  68             strings+=( "$x" )
  69         done
  70     else
  71         strings=( "$@" )
  72     fi
  73
  74     if $file_exists; then
  75         # fix files with no newline at the end.
  76         # the following command won't work right on them.
  77         # e = run script, $a\ means append following text, but there is none,
  78         # so sed only does what it always does when it was supposed to modify a file,
  79         # which is append a newline if there was none.
  80         sed -ie '$a\' "$file"
  81         # this removes any trailing newline in the var, so we add it back on,
  82         # because we want a consistent ending to match
  83         local file_content
  84         if $readsudo; then
  85             file_content="$(sudo cat "$file")
  86 "
  87         else
  88             file_content="$(<"$file")
  89 "
  90         fi
  91         # we aren't using regex because we want to match strings,
  92         # but we also want our match to start at the beginning of a line,
  93         # or the beginning of the file, and to end at a line ending.
  94         # So we do some slick bash to match this.
  95         local start="?(*
  96 )"
  97         local end="
  98 *"
  99         for string in "${strings[@]}"; do
 100             [[ $file_content != $start"$string"$end ]] && $writesudo tee -a "$file"<<<"$string"
 101         done
 102     else
 103         for string in "${strings[@]}"; do
 104             $writesudo tee -a "$file"<<<"${strings[@]}"
 105         done
 106     fi
 107     return 0
 108 }