mail/wrapper/mail-wrapper

   1 #!/usr/bin/env bash
   2 #
   3 # mail-wrapper -- Report results of a command by email
   4 # Copyright (c)2017 Alexander Barton (alex@barton.de)
   5 #
   6 # This program is free software; you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation; either version 2 of the License, or
   9 # (at your option) any later version.
  10 #
  11
  12 NAME=$(basename "$0")
  13
  14 # Include "ax-common.sh":
  15 ax_common_sourced=
  16 for dir in "$HOME/lib" "$HOME/.ax" /usr/local /opt/ax /usr; do
  17         [ -z "$ax_common_sourced" ] || break
  18         ax_common="${dir}/lib/ax/ax-common.sh"
  19         # shellcheck source=/usr/local/lib/ax/ax-common.sh
  20         [ -r "$ax_common" ] && . "$ax_common"
  21 done
  22 if [ -z "$ax_common_sourced" ]; then
  23         echo "Error ($NAME): \"ax-common.sh\" not found, aborting!" >&2
  24         echo "Please install 'ax-unix', \"Alex' UNIX Tools & Scripts\", and try again."
  25         exit 99
  26 fi
  27 unset dir ax_common ax_common_sourced
  28
  29 usage() {
  30         {
  31                 echo
  32                 echo "Usage:"
  33                 echo "  $NAME [--help|--usage]"
  34                 echo "  $NAME {parameters} [<command> [<arg> [<…>]]]"
  35                 echo
  36                 echo "  -C                      Use the \"C\" locale, no localized (error) messages."
  37                 echo "  --errors|-e             Generate email on errors only."
  38                 echo "  --from|-f               Email address of the sender of the email."
  39                 echo "  --subject|-s <subject>  Subject for the email."
  40                 echo "  --to|-t <address>       Email address to send the email to."
  41                 echo
  42                 echo "When no <command> is given, $NAME reads from standard input."
  43                 echo
  44         } >&2
  45         exit "${1:-0}"
  46 }
  47
  48 syntax_error() {
  49         ax_error -l "Syntax error!"
  50         usage 2
  51 }
  52
  53 clean_up() {
  54         if [[ -z "$proc_fd_works" ]]; then
  55                 ax_debug "Cleaning temporary files ..."
  56                 [[ -n "$buffer_file" ]] && rm -f "$buffer_file"
  57                 [[ -n "$error_file" ]] && rm -f "$error_file"
  58         fi
  59 }
  60
  61 case "$(uname)" in
  62         "Darwin")
  63                 unset proc_fd_works
  64                 ;;
  65         *)
  66                 proc_fd_works=1
  67 esac
  68
  69 # Initialize internal state.
  70 unset is_error
  71 host=$(hostname -f 2>/dev/null || hostname)
  72
  73 trap clean_up EXIT
  74
  75 # Some defaults (can be adjusted by command line parameters).
  76 unset do_errors_only
  77 unset subject
  78 from="${LOGNAME:-root} <${LOGNAME:-root}@$host>"
  79 to="$from"
  80
  81 # Parse the command line ...
  82 while [[ $# -gt 0 ]]; do
  83         case "$1" in
  84                 "-C")
  85                         unset LANG
  86                         export LC_ALL="C"
  87                         ;;
  88                 "--debug"|"-D")
  89                         export DEBUG=1
  90                         ;;
  91                 "--errors"|"-e")
  92                         do_errors_only=1
  93                         ;;
  94                 "--from"|"-f")
  95                         shift
  96                         [[ $# -gt 0 ]] || syntax_error
  97                         from="$1"
  98                         ;;
  99                 "--help"|"--usage")
 100                         usage
 101                         ;;
 102                 "--subject"|"-s")
 103                         shift
 104                         [[ $# -gt 0 ]] || syntax_error
 105                         subject="$1"
 106                         ;;
 107                 "--suppress-empty")
 108                         # Ignore this switch for compatibility with an other
 109                         # "mail-wrapper" script. This is the default anyway!
 110                         ;;
 111                 "--to"|"-t")
 112                         shift
 113                         [[ $# -gt 0 ]] || syntax_error
 114                         to="$1"
 115                         ;;
 116                 "-"*)
 117                         syntax_error
 118                         ;;
 119                 *)
 120                         # Command to execute follows in command line.
 121                         break
 122                         ;;
 123         esac
 124         shift
 125 done
 126
 127 # Initialize the "buffer file" on file handle #3. This file will store all
 128 # output, stdout and stderr combined. The file is immediately unliked so that
 129 # we can't leak stale files. Afterwards this script accesses the "buffer file"
 130 # by its file descriptor only.
 131 buffer_file=$(mktemp) \
 132         || ax_abort -l "Failed to create buffer file: \"$buffer_file\"!"
 133 ax_debug "buffer_file=\"$buffer_file\""
 134 exec 3>"$buffer_file" \
 135         || ax_abort -l "Failed to redirect FD #3 to buffer file!"
 136 if [[ -n "$proc_fd_works" ]]; then
 137         rm "$buffer_file" \
 138                 || ax_error -l "Failed to delete buffer file: \"$buffer_file\"!"
 139         buffer_file="/dev/fd/3"
 140 fi
 141
 142 if [[ $# -gt 0 ]]; then
 143         # Execute command and save output in buffer file.
 144         # Use a sub-shell to not pollute our name space!
 145         error_file=$(mktemp) \
 146                 || ax_abort -l "Failed to create error buffer file: \"$error_file\"!"
 147         ax_debug "error_file=\"$error_file\""
 148         exec 4>"$error_file" \
 149                 || ax_abort -l "Failed to redirect FD #4 to error file!"
 150         if [[ -n "$proc_fd_works" ]]; then
 151                 rm "$error_file" \
 152                         || ax_error -l "Failed to delete error buffer file: \"$error_file\"!"
 153                 error_file="/dev/fd/4"
 154         fi
 155
 156         job=$(basename "$1")
 157
 158         ax_debug "Running command \"$*\" ..."
 159         exit_code=$(
 160                 "$@" 2>&1 1>&3 | tee "$error_file" >&3
 161                 echo "${PIPESTATUS[0]}"
 162         )
 163 else
 164         # Read from stdin and save it to the buffer file.
 165         error_file="/dev/null"
 166         job="Job"
 167
 168         ax_debug "Reading from stdin ..."
 169         while read -r line; do
 170                 echo "$line" >&3 \
 171                         || ax_abort -l "Failed to write to buffer file!"
 172         done
 173         exit_code=0
 174 fi
 175
 176 ax_debug "exit_code=$exit_code"
 177
 178 count_all=$(wc -l <"$buffer_file" || ax_abort -l "Failed to count buffer file!")
 179 count_err=$(wc -l <"$error_file" || ax_abort -l "Failed to count error file!")
 180
 181 # Error or no error -- that's the question! An error is assumed when either the
 182 # exit code of the command was non-zero or there was output to stderr.
 183 [[ $count_err -gt 0 || $exit_code -ne 0 ]] && is_error=1
 184
 185 # Construct email subject ...
 186 [[ -z "$subject" ]] && subject="$host: $job report"
 187 [[ -n "$is_error" ]] && subject="$subject - ERROR!" || subject="$subject - success"
 188
 189 ax_debug "from=\"$from\""
 190 ax_debug "to=\"$to\""
 191 ax_debug "subject=$subject"
 192
 193 if [[ -n "$DEBUG" ]]; then
 194         echo "--- stdout+stderr ---"
 195         cat "$buffer_file"
 196         echo "--- stderr ---"
 197         cat "$error_file"
 198         echo "---"
 199 fi
 200
 201 ax_debug "count_all=$count_all"
 202 ax_debug "count_err=$count_err"
 203 ax_debug "is_error=$is_error"
 204
 205 # No errors detected (exit code & stderr), and email should be sent on errors
 206 # only: so exit early!
 207 [[ -z "$is_error" && -n "$do_errors_only" ]] && exit $exit_code
 208
 209 # No error detected and no output at all: skip email, exit early:
 210 [[ -z "$is_error" && $count_all -eq 0 ]] && exit $exit_code
 211
 212 # Build the report mail.
 213 # Make sure to ignore all mail(1) configuration files, system wide /etc/mailrc
 214 # (by using the "-n" option) as well as ~/.mailrc (by setting the MAILRC
 215 # environment varialbe).
 216 export MAILRC=/dev/null
 217 (
 218         echo "$job report:"
 219         echo
 220         echo " - Host: $host"
 221         echo " - User: $(id -un)"
 222         echo " - Exit code: $exit_code"
 223         echo
 224         if [[ $# -gt 0 ]]; then
 225                 # A command name is known (not stdin), show it!
 226                 echo "Command:"
 227                 echo "$@"
 228                 echo
 229         fi
 230         if [[ $count_err -gt 0 ]]; then
 231                 # Prefix mail with all error messages.
 232                 echo "Error summary:"
 233                 echo "-----------------------------------------------------------------------------"
 234                 cat "$error_file" \
 235                         || ax_abort -l "Failed to dump error file!"
 236                 echo "-----------------------------------------------------------------------------"
 237                 echo
 238         fi
 239         if [[ $count_all -ne $count_err ]]; then
 240                 # Show full output when different to "error output" only.
 241                 cat "$buffer_file" \
 242                         || ax_abort -l "Failed to dump buffer file!"
 243         fi
 244 ) | mail -n -a "From: $from" -s "$subject" "$to" \
 245         || ax_abort -l "Failed to send email to \"$to\"!"
 246
 247 exit $exit_code