troubleshooting a cron job - Ubuntu 24.04

Server maintenance - I had put in a cron job to alert me when disk space crosses a threshold - following this -

https://hnsws.blogspot.com/2021/02/scripts-to-alert-admin-when-hard-disk.html

https://www.linuxjournal.com/content/tech-tip-send-email-alert-when-your-disk-space-gets-low

and another to alert me when load average crosses 0.8 * number of CPUs, following this - 
https://gist.github.com/santhoshvr/bd6db5b1cab4f8d181d2ac2b59dd08aa

(need to install bc to get this to work - sudo apt install bc)

The disk space cron was working, but the load average cron would not work - it would work if run from the command-line when I tested by putting in a threshold like 0.01, but not in the cron.

Troubleshooting the cron with the techniques given here - 

https://serverfault.com/questions/449651/why-is-my-crontab-not-working-and-how-can-i-troubleshoot-it

/var/log/cron

or

var/log/syslog

don't exist on this minimal install of Ubuntu 24.04.

Neither does /var/spool/mail/root - /var/spool/mail is empty.

So, trying to redirect errors to a log file with 2>&1

loadalert.sh  > /path/to/loadalertcron.log 2>&1

That log file showed /path/to/loadalert.sh: 22: 1: not found

Turns out it was bash which was not being found, since the "if" command was triggering the "not found". In the first line, the #!/bin/bash had a missing ! - and the path to bash, found with
which bash
was actually /usr/bin/bash and not /bin/bash

So, just changed the first line to

#!/usr/bin/bash

and the script started working fine in the cron job.