Cron not executing Shell Script on Ubuntu - cron

Question

I have a remote .sh script to take backup of mySQL file. Cron is running by .sh file not executing. Content of Crontab are:
#SHELL=/bin/bash PATH=/bin:/sbin:/usr/bin:/usr/sbin
* * * * * /home/ubuntu/dscript/db_backup.sh > /tmp/db.output
File Contents are:
#!/bin/bash
DATE=$(date +%Y%m%d_%H%M)
zipname="db_prod_$DATE.sql"
mysqldump db_prod > $zipname
aws s3 mv $zipname s3://mybackups/$zipname
rm -rf $zipname
zipname="db_staging_$DATE.sql"
mysqldump db_staging > $zipname
aws s3 mv $zipname s3://mybackups/$zipname
rm -rf $zipname
Bash path
bash: /bin/bash /etc/bash.bashrc /usr/share/man/man1/bash.1.gz
I am on Ubuntu.
File is is in +x mode.

Answer 1

#!/usr/bin/bash
DATE=$(date +%Y%m%d_%H%M)
zipname="db_prod_$DATE.sql"
SCRIPT_LOG_FILE="/tmp/backup.log"
echo "[${DATE}] [INFO] Starting personnal backup" > ${SCRIPT_LOG_FILE}
$(which mysqldump) db_prod > $zipname
if [ "$?" -eq "0" ] && [ -f ${zipname} ];then
echo "[$(date +%Y%m%d_%H%M)] [INFO] Mysqldump save file ${zipname}" > ${SCRIPT_LOG_FILE}
# file is created continue job with this file ...
$(which aws) s3 mv $zipname s3://mybackups/$zipname
rm -rf $zipname
else
echo "[$(date +%Y%m%d_%H%M)] [ERROR] Mysqldump can't save file ${zipname}" > ${SCRIPT_LOG_FILE}
fi
exit 0
And crontab -l must be:
* * * * * /home/ubuntu/dscript/db_backup.sh &> /tmp/error.and.result.db.output

Answer 2

check cron error:
try to see error with:
~$ sudo cat /var/log/syslog|grep CRON|grep db_backup.sh
~$ sudo cat /var/log/syslog|grep CRON|grep MY_USERNAME
(Permission denied or other)
where MY_USERNAME is the user execute : crontab -e
check script error:
* * * * * /home/ubuntu/dscript/db_backup.sh > /tmp/result.db.output
* * * * * /home/ubuntu/dscript/db_backup.sh 2> /tmp/error.db.output
or simply
* * * * * /home/ubuntu/dscript/db_backup.sh &> /tmp/error.and.result.db.output
The question is whether the error comes from the execution of cron or is in the script, the above methods will help you find the source of the problem.