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. Duplicate
  13 LINE_SETs are treated the same.
  14
  15   --           stop processing arguments
  16   [-h|--help]  display this message"
  17
  18
  19     while true; do
  20         if [[ $1 == --help || $1 == -h ]]; then
  21             echo "$help"
  22             return
  23         elif [[ $1 == -- ]]; then
  24             shift
  25             break
  26         else
  27             break
  28         fi
  29     done
  30
  31     if [[ ${#@} == 0 ]]; then
  32         echo "error: need 1 or more arguments"
  33         echo "$help"
  34         return 1
  35     fi
  36
  37     local file="$1"
  38     shift
  39
  40     local new_file=true
  41     if [[ -e $file ]]; then
  42         new_file=false
  43     else
  44         local dir="$(dirname "$file")"
  45         if [[ ! -d $dir ]]; then
  46             echo "appendu error: $dir does not exist"
  47             return 1
  48         fi
  49     fi
  50
  51     local strings line
  52     if (( $# == 0 )); then
  53         unset IFS
  54         while read -r line; do
  55             strings+=( "$line" )
  56         done
  57     else
  58         strings=( "$@" )
  59     fi
  60
  61     if ! $new_file; then
  62         if [[ ! -r $file ]]; then
  63             echo "appendu error: cannot read or write $file"
  64             return 1
  65         fi
  66         if [[ ! -w $file ]]; then
  67             echo "appendu error: cannot read or write $file"
  68             return 1
  69         fi
  70         # fix files with no newline at the end.
  71         # the following command won't work right on them otherwise.
  72         # e = run script, $a\ means append following text, but there is none,
  73         # so sed only does what it always does when it was supposed to modify a file,
  74         # which is append a newline if there was none.
  75         sed -ie '$a\' "$file"
  76         # command substitution removes any trailing newlines, so we have to add
  77         # a non-newline ending, we randomly chose "b", then remove it.
  78         local content=$(cat "$file"; echo b) content=${content%b}
  79     fi
  80
  81     # we aren't using regex because we want to match strings,
  82     # but we also want our match to start at the beginning of a line,
  83     # or the beginning of the file, and to end at a line ending.
  84     # So we do some slick bash to match this.
  85     local start="?(*
  86 )"
  87     local end="
  88 *"
  89     local return_code string return_code
  90     for string in "${strings[@]}"; do
  91         if $new_file || [[ $content != $start"$string"$end ]]; then
  92             if ! tee -a "$file"<<<"$string"; then
  93                 return_code=$?
  94                 echo "appendu error: error writing to $file"
  95                 return $return_code
  96             fi
  97         fi
  98     done
  99     return 0
 100 }