root@localhost:~$ date +"%Y_%m_%d_%H_%M"
2019_07_24_00_15
root@localhost:~$ date +"%Y_%m_%d_%H_%M_%S"
2019_07_24_00_15_48
root@localhost:~$ date +"%Y%m%d_%H_%M_%S"
20190724_00_16_01
lake@localhost:~$

#/bin/bash

LOG_FAIL_LIST=$TMP/log_fail_list`date +"%Y_%m_%d_%H_%M"`.txt

while [ "1" = "1" ]

do

 echo "`date +"%Y_%m_%d_%H_%M"` Ascii from PC Host to RS485/UART    "  > /dev/ttymxc3  
 echo "`date +"%Y_%m_%d_%H_%M"` Ascii from PC Host to RS485 BUS2  "  > /dev/ttymxc4

done
 

#### Set 

# date  -s   2020.02.02-12:22:11
Sun Feb  2 12:22:11 UTC 2020
 #