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

   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     if ! $new_file; then
  51         if [[ ! -r $file ]]; then
  52             echo "appendu error: cannot read or write $file"
  53             return 1
  54         fi
  55         if [[ ! -w $file ]]; then
  56             echo "appendu error: cannot read or write $file"
  57             return 1
  58         fi
  59     fi
  60
  61     local strings
  62     if (( $# == 0 )); then
  63         unset IFS
  64         while read -r x; do
  65             strings+=( "$x" )
  66         done
  67     else
  68         strings=( "$@" )
  69     fi
  70
  71     if $new_file; then
  72         # fix files with no newline at the end.
  73         # the following command won't work right on them otherwise.
  74         # e = run script, $a\ means append following text, but there is none,
  75         # so sed only does what it always does when it was supposed to modify a file,
  76         # which is append a newline if there was none.
  77         sed -ie '$a\' "$file"
  78         # command substitution removes any trailing newlines, so we have to add
  79         # a non-newline ending, we randomly chose "b", then remove it.
  80         local content=$(cat "$file"; echo b) content=${content%b}
  81     fi
  82
  83     # we aren't using regex because we want to match strings,
  84     # but we also want our match to start at the beginning of a line,
  85     # or the beginning of the file, and to end at a line ending.
  86     # So we do some slick bash to match this.
  87     local start="?(*
  88 )"
  89     local end="
  90 *"
  91     local return_code string return_code
  92     for string in "${strings[@]}"; do
  93         if $new_file || [[ $content != $start"$string"$end ]]; then
  94             if ! tee -a "$file"<<<"$string"; then
  95                 return_code=$?
  96                 echo "appendu error: error writing to $file"
  97                 return $return_code
  98             fi
  99         fi
 100     done
 101     return 0
 102 }
 103 appendu "$@"