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 cbase c log x i out file
  21   cbase=/var/local/cron-errors
  22   [[ $EUID == 0 ]] || cbase=$HOME/cron-errors
  23   local help="Usage: log-once [OPTION]... LOG_NAME [LOG_MESSAGE]
  24
  25 For cronjobs, email log on repeated failure and success after failure.
  26
  27 Meant for use in cronjobs where LOG_MESSAGE or STDIN represents an error,
  28 but we only want to output that to STDOUT if we've seen this type of
  29 error ERRORS(default 3) number of times in a row, then we don't
  30 want to output anything again until we've seen a success (an empty LOG_MESSAGE).
  31
  32 Logs LOG_MESSAGE or STDIN to /var/local/cron-errors/LOG_NAME\$error_count
  33 or $HOME/cron-errors if not root, and keeps
  34 state in the same directory.
  35
  36 -ERRORS:  ERRORS is the number of errors to accumulate before outputing the error"
  37   errors=3
  38   while true; do
  39     if [[ $1 == --help ]]; then
  40       echo "$help"
  41       return
  42     elif [[ $1 == -[0-9]* ]]; then
  43       errors=${1#-}
  44       shift
  45     elif [[ $1 == -- ]]; then
  46       shift
  47       break
  48     else
  49       break
  50     fi
  51   done
  52   log_name=$1
  53   # todo, make option & make them overridable based on command line or env variable
  54   [[ -d $cbase ]] || mkdir -p $cbase
  55   c=$cbase/$log_name
  56   # http://stackoverflow.com/questions/2456750/detect-presence-of-stdin-contents-in-shell-script
  57   log=false
  58   if [[ $2 ]]; then
  59     log=true
  60     # read stdin for anything which is not just a newline
  61   elif [[ ! -t 0 ]]; then
  62     while read -r x; do
  63       output+=( $x )
  64       [[ $x ]] && log=true
  65     done
  66   fi
  67   glob="$c[0-9]*"
  68   file=($glob); [[ $file != "$glob" ]] || file=
  69   if $log; then
  70     out=append
  71     if [[ $file ]]; then
  72       i="${file#$c}"
  73       if (( i < errors )); then
  74         new_file=$c$((i+1))
  75         mv $file $new_file
  76         file=$new_file
  77         if [[ $file == $c$errors ]]; then
  78           out="tee -a"
  79         fi
  80       fi
  81     else
  82       file=${c}1
  83     fi
  84     $out $file <<<"log-once: $(date "+%A, %B %d, %r")"
  85     if [[ $2 ]]; then
  86       $out $file <<<"$2"
  87     else
  88       $out $file <<<"${output[@]}"
  89       $out $file
  90     fi
  91     return 0
  92   fi
  93   if [[ $file ]]; then
  94     rm -f $file
  95     if [[ $file == $c$errors ]]; then
  96       echo "log-once success after failure for $c"
  97     fi
  98   fi
  99   return 0
 100 }
 101 log-once "$@"