Thanks Warren for pointing me at the backup function in SQLite itself. At the moment I have managed to get a simple copy of the database file to a remote location working, so that is a start. This sounds like a more fault tolerant approach as the database engine is managing both any potential writes and the backup process to void conflicts.
My simple approach is taking seconds to execute, so judicious timing of the cron job is working for the present. Appreciate you taking the time to chime in. As you say, good to have someone challenging your assumptions rather than just diving deeper down the rabbit hole you're currently stuck in. On Tuesday, September 22, 2026 at 12:59:55 PM UTC+10 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 >>>>> ``` >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "weewx-user" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected]. >>>>> To view this discussion visit >>>>> https://groups.google.com/d/msgid/weewx-user/df76a922-ace3-44ae-a65a-0a50b6f8fe92n%40googlegroups.com >>>>> >>>>> <https://groups.google.com/d/msgid/weewx-user/df76a922-ace3-44ae-a65a-0a50b6f8fe92n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- >>> You received this message because you are subscribed to the Google >>> Groups "weewx-user" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> >> To view this discussion visit >>> https://groups.google.com/d/msgid/weewx-user/346dd346-60e0-4fc9-8083-ee1c6b58c8dfn%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/weewx-user/346dd346-60e0-4fc9-8083-ee1c6b58c8dfn%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> >> -- You received this message because you are subscribed to the Google Groups "weewx-user" group. 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