pg_start/stop_backup non-exclusive scripts to snapshot

Hi there,

I’ve previously done ZFS snapshot backups like this:

psql -c “select pg_start_backup(‘snapshot’);”
zfs snapshot TANK/postgresql(at)`date ‘+%Ymd’`
psql -c “select * from pg_stop_backup();”

Reading the PostgreSQL9.6 documentation, the advice/future is to use the non-exclusive method, where I’ll need to keep a session *open* while the snapshot takes place, and after that I’ll have to issue the pg_stop_backup(false); in that active connection that issued the pg_start_backup(‘backup’,false,false);

How is this done inside a shell script?
Especially how to do error checking from the commands as psql -c “select pg_start_backup{‘test’,false,false);” not going to work?

Hendrik