iankelling.org Git - log-quiet/blob - log-once

   1 #!/bin/bash
   2 # Copyright (C) 2016 Ian Kelling
   3
   4 # Licensed under the Apache License, Version 2.0 (the "License");
   5 # you may not use this file except in compliance with the License.
   6 # You may obtain a copy of the License at
   7
   8 #     http://www.apache.org/licenses/LICENSE-2.0
   9
  10 # Unless required by applicable law or agreed to in writing, software
  11 # distributed under the License is distributed on an "AS IS" BASIS,
  12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 # See the License for the specific language governing permissions and
  14 # limitations under the License.
  15
  16 append() {
  17     cat >> "$1"
  18 }
  19 log-once() {
  20     local help="Usage: log-once [OPTION]... LOG_NAME [LOG_MESSAGE]
  21
  22 For cronjobs, email only once for repeated failures, and for success after failure.
  23
  24 Meant for use in cronjobs where LOG_MESSAGE or STDIN represents an error,
  25 but we only want to output that to STDOUT if we've seen this type of
  26 error ERRORS(default 3) number of times in a row, then we don't
  27 want to output anything again until we've seen a success (an empty LOG_MESSAGE).
  28
  29 Logs LOG_MESSAGE or STDIN to ~/.cron_errors/LOG_NAME, and keeps
  30 state in the same directory.
  31
  32 -e ERRORS:  ERRORS is the number of errors to accumulate before outputing the error"
  33     local cbase c c1 c2 log x i out file
  34     errors=3
  35     while true; do
  36         if [[ $1 == --help ]]; then
  37             echo "$help"
  38             return
  39         elif [[ $1 == -[0-9]* ]]; then
  40             errors={$1#-}
  41             shift
  42         elif [[ $1 == -- ]]; then
  43             shift
  44             break
  45         else
  46             break
  47         fi
  48     done
  49     log_name=$1
  50     # todo, make option & make them overridable based on command line or env variable
  51     cbase=$HOME/.cron-errors
  52     [[ -d $cbase ]] || mkdir -p $cbase
  53     c=$cbase/$log_name
  54     # http://stackoverflow.com/questions/2456750/detect-presence-of-stdin-contents-in-shell-script
  55     log=false
  56     if [[ $2 ]]; then
  57         log=true
  58         # read stdin for anything which is not just a newline
  59     elif [[ ! -t 0 ]]; then
  60         while read -r x; do
  61             output+=( $x )
  62             [[ $x ]] && log=true
  63         done
  64     fi
  65     if $log; then
  66         file=
  67         if [[ -f $c$((errors-1)) ]]; then
  68             out="tee -a"
  69         else
  70             out=append
  71         fi
  72         for ((i=errors; i>=1; i--)); do
  73             if [[ -f $c$((i-1)) ]]; then
  74                 file=$c$i
  75                 mv $c$((i-1)) $file
  76                 break
  77             fi
  78         done
  79         if [[ ! $file ]]; then
  80             if [[ -f $c$errors ]]; then
  81                 file=$c$errors
  82             else
  83                 file=${c}1
  84             fi
  85         fi
  86         $out $file <<<"log-once: $(date "+%A, %B %d, %r")"
  87         if [[ $2 ]]; then
  88             $out $file <<<"$2"
  89         else
  90             $out $file <<<"${output[@]}"
  91             $out $file
  92         fi
  93         return 1
  94     elif [[ -f $c$errors ]]; then
  95         echo "log-once success after failure for $c"
  96         rm -f $c$errors
  97     else
  98         rm -f $c[0-9]* # assuming  no one is putting crazy files names, as this is not exact
  99     fi
 100     return 0
 101 }
 102 log-once "$@"