The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/9.6/static/continuous-archiving.html
Description:
Seems to need a persistent connection:
<quote>
25.3.3.1. Making a non-exclusive low level backup
...
The connection calling pg_start_backup must be maintained until the end of
the backup, or the backup will be automatically aborted.
...
</Quote>
The sample works with a NON-persistent connection (psql -c):
<quote>
25.3.6.1. Standalone Hot Backups
... touch /var/lib/pgsql/backup_in_progress
psql -c "select pg_start_backup('hot_backup');"
tar -cf /var/lib/pgsql/backup.tar /var/lib/pgsql/data/
psql -c "select pg_stop_backup();"
rm /var/lib/pgsql/backup_in_progress
tar -rf /var/lib/pgsql/backup.tar /var/lib/pgsql/archive/
...
</quote>