Show a back trace in bash with context lines.

bash_stack_trace.bash

# Prints the stack trace and some context lines for where the stack trace happened

# rotate the log
unlink /var/rotating_log.log
datetime=$(date +%m%d%Y_%H%M%S);
logfile="rotating_log_$datetime.log"
echo "Started on $datetime" > $logfile
#chfile mygroup 664 $logfile
ln -s $logfile rotating_log.log

# show the output in stdout and in the log file
exec &> >(tee -a $logfile)

function stack_trace() # requires a variable called $logfile
   echo "stack:" >> $logfile
   local frame=0
   # caller is only available in bash
   # http://wiki.bash-hackers.org/commands/builtin/caller
   while caller $frame >> $logfile; do
      ((frame++))
   done
   echo "end of stack" >> $logfile

   # show the 5 previous lines leading up to the call to stack_trace
   local start=$(expr ${BASH_LINENO[0]} - 5)
   context_lines=$(sed ''"$start"','"${BASH_LINENO[0]}"'!d' "${BASH_SOURCE[1]}" | nl -ba -v$start)
   cat <<EOF >> $logfile
    >>>
error in: ${BASH_SOURCE[1]}
$context_lines
   <<<
EOF
}

# example usage
# TODO fix the bug below
echo "Bug 12345"
stack_trace()