While I use MariaDB and create hot DB backups, for small databases like
weewx, there is nothing wrong with a cold backup (where the database is
stopped, backed up and started up).
---
pablo
On 2026-09-21 22:59, Warren Gill wrote:
The AI is not "drivel" but it's also not really helpful. AI tends to
keep leading you down the same incorrect path just to fulfill your
instruction. SQLite3 has included a backup API since 3.3.0. There's no
need to stop/start/quiesce just use the .backup command.
https://www.sqlite.org/backup.html
Most of this script is error checking stuff I borrowed from my other
error checking stuff. It really just boils down to:
*sqlite3 /var/lib/weewx/weewx.sdb ".backup /var/tmp/weewx-$(date
+%Y%m%d)-backup.sdb"*
Here's the whole script nonetheless:
#!/usr/bin/env bash
set -Eeuo pipefail
# Uses SQLite Online Backup API
# https://www.sqlite.org/backup.html
# Logs to journal
# View the logs with journalctl -t weewx-backup --since "1 hour ago"
#
# Add to crontab to run daily at 2 AM:
# MAILTO="[email protected]"
# 0 2 * * * /usr/bin/env bash /usr/local/bin/weewx-backup.sh
#
DB="/var/lib/weewx/weewx.sdb"
BACKUPDIR="/var/tmp/wxbackups"
TIMESTAMP="$(date +%Y%m%d-%H%M%S)"
BACKUP_PATH="${BACKUPDIR}/weewx-${TIMESTAMP}.sdb"
ARCHIVE_PATH="${BACKUP_PATH}.gz"
mkdir -p "$BACKUPDIR"
exec 1> >(logger -t weewx-backup) 2>&1
log() {
echo "[$(date -Is)] $*"
}
log "Starting weewx backup"
if [ ! -f "$DB" ]; then
log "ERROR: database not found: $DB"
exit 1
fi
if ! command -v sqlite3 >/dev/null 2>&1; then
log "ERROR: sqlite3 is not installed"
exit 1
fi
log "Creating SQLite backup: $BACKUP_PATH"
if ! sqlite3 "$DB" ".backup '$BACKUP_PATH'"; then
log "ERROR: SQLite backup failed"
exit 1
fi
log "Checking database integrity"
if ! sqlite3 "$BACKUP_PATH" "PRAGMA integrity_check;" | grep -qi
'^ok$'; then
log "ERROR: backup integrity check failed"
rm -f "$BACKUP_PATH"
exit 1
fi
log "Compressing backup"
gzip -9 "$BACKUP_PATH"
log "Removing backups older than 30 days"
find "$BACKUPDIR" -type f -name 'weewx-*.sdb.gz' -mtime +30 -delete
log "Backup complete: $ARCHIVE_PATH"
exit 0
On Monday, September 21, 2026 at 8:47:49 PM UTC-5 Pablo Sanchez wrote:
I found the Gen AI response on point.
What's more disconcerting would be a single person dictating what
is and what isn't allowed to be posted to a worldwide list.
---
pablo
On September 21, 2026 20:55:14 John Bonzey <[email protected]> wrote:
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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