Run a bash script one and stop - mysql

Question

I have this simple script that checks if mysql on remote servers (db-test-1 and db-test-2) is in SST mode and sends a message to a slack channel. The script is running on a third server dedicated for running cron jobs. Here is the code below:
#!/bin/bash
time=$(date);
array=( db-test-1 db-test-2 )
for i in "${array[#]}"
do
S=$(ssh $i ps -ef |grep mysql | grep wsrep_sst_xtrabackup-v2);
if [[ "$S" != "" ]]; then
curl -X POST --data-urlencode "payload={\"channel\": \"#db-share-test\", \"username\": \"wsrep_local_state_comment\", \"text\": \"*$i*: ${time}\n>State transfer in progress, setting sleep higher mysqld\", \"icon_emoji\": \":scorpion:\"}" https://hooks.slack.com/services/G824ZJS9N/B6QS5JEKP/ZjV1hmM1k4dZGsf9HDC1o1jd
exit 0
else
curl -X POST --data-urlencode "payload={\"channel\": \"#db-share-test\", \"username\": \"wsrep_local_state_comment\", \"text\": \"*$i*: ${time}\n>State transfer is complete. Server is Synced now.\", \"icon_emoji\": \":scorpion:\"}" https://hooks.slack.com/services/G824ZJS9N/B6QS5JEKP/ZjV1hmM1k4dZGsf9HDC1o1jd
exit 2
fi
done
The two servers, db-test1 and db-test-2 are part of a PXC cluster. So when i start db-test-1 in SST to join the cluster, i get the following in my slack channel as expected:
*db-test-1*: Sun Aug 27 15:12:44 CST 2017
>State transfer in progress, setting sleep higher mysqld
[3:12]
*db-test-1*: Sun Aug 27 15:12:49 CST 2017
State transfer in progress, setting sleep higher mysqld
[3:12]
*db-test-1*: Sun Aug 27 15:12:51 CST 2017
State transfer in progress, setting sleep higher mysqld
[3:12]
*db-test-1*: Sun Aug 27 15:12:54 CST 2017
State transfer in progress, setting sleep higher mysqld
So the results are being displayed approximately every 3 seconds. However, the cron job executing this script is scheduled to run every minute, hence not sure why it is sending results every 3 seconds or so as shown above.
How can i ensure that the results are displayed every 1 minute to avoid my channel being thrown the same message every 3 seconds? Also, how can i make sure that when the SST is finished, a single message to slack to indicate that the state transfer is finished instead of sending this message none-stop every time the two db servers are not in SST mode?

Answer 1

Besides checking that the cron is properly set, probably something like:
#every_minute /path/to/script
or
*/1 * * * * /path/to/script
It could be also good to ensure that only one occurrence of the program is running, try adding this to your script used within the cron job
*/1 * * * * pgrep script > /dev/null || /path/to/script
or by using something like:
#!/bin/sh
if ps -ef | grep -v grep | grep your_script_name ; then
exit 0
fi
# your code goes below
# ...