16.3. Applications

   1 #!/bin/bash
   2 # logevents.sh, by Stephane Chazelas.
   3 
   4 # Event logging to a file.
   5 # Must be run as root (for write access in /var/log).
   6 
   7 ROOT_UID=0     # Only users with $UID 0 have root privileges.
   8 E_NOTROOT=67   # Non-root exit error.
   9 
  10 
  11 if [ "$UID" -ne "$ROOT_UID" ]
  12 then
  13   echo "Must be root to run this script."
  14   exit $E_NOTROOT
  15 fi  
  16 
  17 
  18 FD_DEBUG1=3
  19 FD_DEBUG2=4
  20 FD_DEBUG3=5
  21 
  22 # Uncomment one of the two lines below to activate script.
  23 # LOG_EVENTS=1
  24 # LOG_VARS=1
  25 
  26 
  27 log()  # Writes time and date to log file.
  28 {
  29 echo "$(date)  $*" >&7     # This *appends* the date to the file.
  30                               # See below.
  31 }
  32 
  33 
  34 
  35 case $LOG_LEVEL in
  36  1) exec 3>&2         4> /dev/null 5> /dev/null;;
  37  2) exec 3>&2         4>&2         5> /dev/null;;
  38  3) exec 3>&2         4>&2         5>&2;;
  39  *) exec 3> /dev/null 4> /dev/null 5> /dev/null;;
  40 esac
  41 
  42 FD_LOGVARS=6
  43 if [[ $LOG_VARS ]]
  44 then exec 6>> /var/log/vars.log
  45 else exec 6> /dev/null               # Bury output.
  46 fi
  47 
  48 FD_LOGEVENTS=7
  49 if [[ $LOG_EVENTS ]]
  50 then
  51   # then exec 7 >(exec gawk '{print strftime(), $0}' >> /var/log/event.log)
  52   # Above line will not work in Bash, version 2.04.
  53   exec 7>> /var/log/event.log        # Append to "event.log".
  54   log                                      # Write time and date.
  55 else exec 7> /dev/null                  # Bury output.
  56 fi
  57 
  58 echo "DEBUG3: beginning" >&${FD_DEBUG3}
  59 
  60 ls -l >&5 2>&4                       # command1 >&5 2>&4
  61 
  62 echo "Done"                                # command2 
  63 
  64 echo "sending mail" >&${FD_LOGEVENTS}   # Writes "sending mail" to fd #7.
  65 
  66 
  67 exit 0