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

   1 #!/bin/bash
   2 # Copyright (C) 2019 Ian Kelling
   3 # SPDX-License-Identifier: AGPL-3.0-or-later
   4
   5 append() {
   6   cat >> "$1"
   7 }
   8 log-once() {
   9   local cbase c log x i out file o tmp
  10   cbase=/var/local/cron-errors
  11   [[ $EUID == 0 ]] || cbase=$HOME/cron-errors
  12   local help="Usage: log-once [OPTION]... LOG_NAME [LOG_MESSAGE...]
  13
  14 For cronjobs, email log on repeated failure and success after failure.
  15
  16 Meant for use in cronjobs where LOG_MESSAGE or STDIN represents an error,
  17 but we only want to output that to STDOUT if we've seen this type of
  18 error ERRORS(default 3) number of times in a row, then we don't
  19 want to output anything again until we've seen a success (an empty LOG_MESSAGE).
  20
  21 Logs LOG_MESSAGE or STDIN to /var/local/cron-errors/LOG_NAME\$error_count
  22 or $HOME/cron-errors if not root, and keeps
  23 state in the same directory.
  24
  25 -ERRORS:  ERRORS is the number of errors to accumulate before outputing the error"
  26   errors=3
  27   while true; do
  28     if [[ $1 == --help ]]; then
  29       echo "$help"
  30       return
  31     elif [[ $1 == -[0-9]* ]]; then
  32       errors=${1#-}
  33       shift
  34     elif [[ $1 == -- ]]; then
  35       shift
  36       break
  37     else
  38       break
  39     fi
  40   done
  41   log_name=$1
  42   # todo, make option & make them overridable based on command line or env variable
  43   [[ -d $cbase ]] || mkdir -p $cbase
  44   c=$cbase/$log_name
  45   # http://stackoverflow.com/questions/2456750/detect-presence-of-stdin-contents-in-shell-script
  46   log=false
  47   if [[ $2 ]]; then
  48     log=true
  49     # read stdin for anything which is not just a newline
  50   elif [[ ! -t 0 ]]; then
  51     while read -r x; do
  52       output+=( "$x" )
  53       [[ $x ]] && log=true
  54     done
  55   fi
  56   glob="$c[0-9]*"
  57   # file is error file indicating previous error
  58   tmp=($glob); file="${tmp[0]}"
  59   if [[ $file == "$glob" ]]; then
  60     file=
  61   fi
  62   if $log; then
  63     out=append
  64     if [[ $file ]]; then
  65       i="${file#$c}"
  66       if (( i < errors )); then
  67         new_file=$c$((i+1))
  68         mv $file $new_file
  69         file=$new_file
  70         if [[ $file == $c$errors ]]; then
  71           out="tee -a"
  72         fi
  73       fi
  74     else
  75       file=${c}1
  76       if (( errors == 1 )); then
  77         out="tee -a"
  78       fi
  79     fi
  80     $out $file <<<"log-once: $(date "+%A, %B %d, %r")"
  81     if [[ $2 ]]; then
  82       $out $file <<<"$*"
  83     else
  84       for o in "${output[@]}"; do
  85         $out $file <<<"$o"
  86       done
  87       $out $file
  88     fi
  89     return 0
  90   fi
  91   if [[ $file ]]; then
  92     rm -f $file
  93     if [[ $file == $c$errors ]]; then
  94       echo "log-once success after failure for $c"
  95     fi
  96   fi
  97   return 0
  98 }
  99 log-once "$@"