Stuart Henderson, 22 Sep 2014 21:09:
> it may be allowed to run it, but ...
> 
> <sthen@hub:~:1278>$ pg_ctl -D /var/postgresql status
> pg_ctl: no server running
> 
> <sthen@hub:~:1279>$ pgrep -lf postg
> 15784 postgres: stats collector process
> 12782 postgres: autovacuum launcher process
> 1792 postgres: wal writer process
> 1744 postgres: writer process
> 27185 postgres: checkpointer process
> 7867 /usr/local/bin/postgres -D /var/postgresql/data

this works for me:

$ sudo /etc/rc.d/postgresql start
postgresql(ok)

$ sudo su - _postgresql
$ pg_ctl -D /var/postgresql/data status
pg_ctl: server is running (PID: 30636)
/usr/local/bin/postgres "-D" "/var/postgresql/data"


> problem with multi-process servers is how to decide which process
> indicates that it's actually running. I'm happier to defer to
> the software's own checks if they make sense (and I think they do
> here).

i would say that for checking the main postgres process
is a good bet.  it also differentiates between -D datadirs,
so it is good for checking multiple instances as well.

regarding the check, i am afraid it is not as good as
it seems.  this is my running instance:

-+- 30636 _postgresql /usr/local/bin/postgres -D /var/postgresql/data
 |--= 07948 _postgresql postgres: checkpointer process    (postgres)
 |--= 30292 _postgresql postgres: wal writer process    (postgres)
 |--= 14555 _postgresql postgres: writer process    (postgres)
 |--= 18537 _postgresql postgres: stats collector process    (postgres)
 \--= 21453 _postgresql postgres: autovacuum launcher process    (postgres)

unfortunately postgres seems to be quite keen on pid files.

$ pg_ctl -D /var/postgresql/data status
pg_ctl: server is running (PID: 30636)
/usr/local/bin/postgres "-D" "/var/postgresql/data"

$ cd /var/postgresql/data
$ mv postmaster.pid postmaster.pid.orig
$ pg_ctl -D /var/postgresql/data status
pg_ctl: no server running

so that is the "check".  it basically prints
postmaster.pid and postmaster.opts
i'll take pgrep any day over that.

-f
-- 
petting: a study of anatomy in braille...

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