m144.sh (m100-m199) to timestamp begin/end of G-code run?

... at beginning of G-code
M144 201 1 ; M144, relies on m144.sh, reminiscent of old AT&T 411 service, followed by modelnumber and "begin" flag 
... do the program
M144 201 0 ; "begin" flag not equal 1, thus, "end"
M5
M2

#!/bin/bash

# Filename: m144.sh
# LinuxCNC log modelnumber and time-of-day

modelnumber=$1 # first arg
begin=$2 # second arg, begin = 1, end = 0

#daat = `date` # FAIL no spaces allowed
daat=`date` # fine, call linux os 'date' command

echo "Model$modelnumber: $daat" >> /CNCMODELS/m144_time.log

if [ $begin -eq 0 ] ; then # my, what strange syntax you have my dear...
  echo '' >> /CNCMODELS/m144_time.log &
fi

exit 0

2.4 [RS274NGC] Section

23. M100-M199 User Defined Commands

The error Unknown M code used denotes one of the following:
*   The specified User Defined Command does not exist
*   The file is not an executable file
*   The file name has an extension
*   The file name does not follow this format M1nn where nn = 00 through 99
*   The file name used a lower case M