Report changes in log file by email

segtail.sh

#!/bin/bash

# Adapted from http://stackoverflow.com/a/4657776/641892

file=$1
subject=$2
size=0
offset=0
recipients="foo@bar"

if [[ $file =~ / ]]; then
   echo "$0 does not accept path components in the file name" 2>&1
   exit 1
fi
if [[ -e .offset.$file ]]; then
   offset=$(<".offset.$file")
   fi
if [[ -e $file ]]; then
   size=$(stat -c "%s" "$file")    # this assumes GNU stat, possibly present as gstat. CHECK!
                                   # (gstat can also be Ganglias Status tool - careful).
fi
if (( $size < $offset )); then     # file might have been reduced in size
   echo "reset offset to zero" 2>&1
   offset=0
fi
echo $size > ".offset.$file"
if [[ -e $file &&  $size -gt $offset ]]; then
   tail -c +$(($offset+1)) "$file" | head -c $(($size - $offset)) | mail -s "$subject ($file)" $recipients
fi