How is it drivel. it gives the completed script with an explanation
On Monday, September 21, 2026 at 8:51:02 PM UTC-4 Vince Skahan wrote:
Please no three page AI drivel. Please.
On Monday, September 21, 2026 at 5:06:31 PM UTC-7 John Bonzey wrote:
Claude says the following;
Subject: Re: bash while loop syntax for weewx backup script
Hi,
I think I spotted the issue. Your while condition is:
while [ systemctl -q is-active weewx ];
The problem is that [ ... ] is the "test" command - it doesn't actually run
systemctl at all. It just checks whether the string "systemctl -q is-active
weewx" is non-empty, which is always true, so the loop never ends based on
weewx's real state (it just happens to work when weewx stops quickly, since
the loop body still runs and eventually you get lucky with timing).
The fix is to drop the [ ] brackets entirely and use the command itself as
the condition. In bash, while just checks the exit status of whatever
command you give it - it doesn't need [ ] at all unless you're testing a
string, number, or file:
while systemctl -q is-active weewx;
do
sleep 1
echo $(date): Weewx is still stopping >> /var/log/weewx-backup.log
done
systemctl -q is-active weewx exits 0 (true) while the service is active,
and non-zero once it's fully stopped - which is exactly what you want the
loop to check.
General rule of thumb: use while [ condition ] for string/number/file
tests, and while some_command when you want to "loop while this command
succeeds."
Your instinct not to copy the DB mid-write is exactly right, and this fix
makes that work as intended.
One more suggestion: it's worth adding a timeout guard in case weewx ever
hangs on stop, so the script can't wait forever. Here's the full script
with that added:
#!/bin/bash
#
# Stop weewx service
echo $(date): Weewx is stopping >> /var/log/weewx-backup.log
systemctl stop weewx
#
# Check service has stopped (with timeout)
timeout=30
count=0
while systemctl -q is-active weewx;
do
if [ $count -ge $timeout ]; then
echo $(date): Weewx did not stop after ${timeout}s - aborting backup >>
/var/log/weewx-backup.log
systemctl start weewx
exit 1
fi
sleep 1
count=$((count + 1))
echo $(date): Weewx is still stopping >> /var/log/weewx-backup.log
done
echo $(date): Weewx has stopped >> /var/log/weewx-backup.log
#
# Copy files to backup folder
echo $(date): Backup is starting >> /var/log/weewx-backup.log
tar -czvf /mnt/backup/weewx-conf.tar.gz /etc/weewx
tar -czvf /mnt/backup/weewx-db.tar.gz /var/lib/weewx/weewx.sdb
echo $(date): Backup is complete >> /var/log/weewx-backup.log
#
# Start weewx service
systemctl start weewx
echo $(date): Weewx is starting >> /var/log/weewx-backup.log
With the timeout added, if weewx ever fails to stop within 30 seconds, the
script restarts weewx, logs the failure, and exits before touching the
backup files - so a hung stop can't leave weewx down or risk copying a
database mid-write.
Hope that helps!
From: [email protected] <[email protected]> on behalf of
David Schulz <[email protected]>
Sent: Monday, September 21, 2026 7:22 PM
To: weewx-user <[email protected]>
Subject: [weewx-user] Assistance with While condition for backup script
Hi
I'm attempting to write my first bash script to backup weewx. I'm
struggling with the syntax of a condition for a while loop that checks if
weewx has stopped or is still stopping.
I don't really understand the syntax of the example conditions I can find
for various tutorials on using while to create a loop. I cannot find
anywhere an exact example of using 'systemctl is-active' as the condition
for a while loop.
Appreciate any feedback from people more learned than I.
TIA
Here's what I have at the moment. If I run this script when I know weewx
won't be writing to the database, the commands to zip the files into the
backup directory all work OK.
I don't think I want to be copying the database file in the middle of a
write. So I have a separate script with the backup section removed just
trying to test the stopping, check has stopped and start parts of the
script. I've been unsuccessfully futzing around with different condition
syntax and actively trying to run it when weewx is active and the stop
command will take a while to execute while the weewx main loop completes.
But TBH I'm just wandering about in the dark.
```
#!/bin/bash
#
# Stop weewx service
echo $(date): Weewx is stopping >> /var/log/weewx-backup.log
systemctl stop weewx
#
# Check service has stopped
while [ systemctl -q is-active weewx ];
do
sleep 1
echo $(date): Weewx is still stopping >> /var/log/weewx-backup.log
done
echo $(date): Weewx has stopped >> /var/log/weewx-backup.log
#
# Copy files to backup folder
echo $(date): Backup is starting >> /var/log/weewx-backup.log
tar -czvf /mnt/backup/weewx-conf.tar.gz /etc/weewx
tar -czvf /mnt/backup/weewx-db.tar.gz /var/lib/weewx/weewx.sdb
echo $(date): Backup is complete >> /var/log/weewx-backup.log
#
# Start weewx service
systemctl start weewx
echo $(date): Weewx is starting >> /var/log/weewx-backup.log
```
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