Error message "psql: could not connect to server: No such file or directory"

On 06/14/2012 06:30 AM, Stefan Schwarzer wrote:

Hi there,

I guess this is a typical user error. I searched around to find the solution, but in vain.

I just upgraded to Lion, and used Kyngchaos libraries for installation of Postgres.

Try to get running postgres, and I get this:

/usr/local/pgsql-9.1/bin/psql -U postgres
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/tmp/.s.PGSQL.5432"?

In my limited understanding, it seems that Postgres is not running. When I use:

ps auxw | grep post

out comes only the "grep post", but no postgres process.

When I use:

sudo launchctl load /Library/LaunchDaemons/org.postgresql.postgres.plist

it says:

org.postgresql.postgres: Already loaded

and displays in the "ps" list then:

user 935 0.0 0.1 2493888 7296 ?? Ss 3:24PM 0:00.12 /System/Library/PrivateFrameworks/DiskImages.framework/Resources/diskimages-helper -uuid 9EFB9424-7971-4A8B-9D73-B93BD7F1DB5F -post-exec 4

(which looks a bit strange to me (DiskImages ??))

I am somewhat lost (and worse is that it worked the other day, before re-installing Lion anew.).

http://www.kyngchaos.com/software/postgres
"
Notes

NOTE: I've had reports of the installer not initializing the data
cluster, which results in Postgres not starting. It seems to be random,
and I haven't figured out the cause yet. If Postgres won't start (you
get an error "could not connect to server: No such file or directory"
when trying to connect with psql), try manually initializing the cluster
with:
/usr/local/pgsql-9.1/bin/initdb -U postgres \
-D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US"
Or see the Locales and Encodings readme if you need a different locale
or encoding.
Then stop and start Postgres as specified in the readme.
"

Thanks for any hints,

Stef

--
Adrian Klaver
adrian.klaver@gmail.com

Hi there,

I guess this is a typical user error. I searched around to find the solution, but in vain.

I just upgraded to Lion, and used Kyngchaos libraries for installation of Postgres.

Try to get running postgres, and I get this:

/usr/local/pgsql-9.1/bin/psql -U postgres
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/tmp/.s.PGSQL.5432"?

In my limited understanding, it seems that Postgres is not running. When I use:

ps auxw | grep post

out comes only the "grep post", but no postgres process.

When I use:

sudo launchctl load /Library/LaunchDaemons/org.postgresql.postgres.plist

it says:

org.postgresql.postgres: Already loaded

and displays in the "ps" list then:

user 935 0.0 0.1 2493888 7296 ?? Ss 3:24PM 0:00.12 /System/Library/PrivateFrameworks/DiskImages.framework/Resources/diskimages-helper -uuid 9EFB9424-7971-4A8B-9D73-B93BD7F1DB5F -post-exec 4

(which looks a bit strange to me (DiskImages ??))

I am somewhat lost (and worse is that it worked the other day, before re-installing Lion anew.).

http://www.kyngchaos.com/software/postgres
"
Notes

NOTE: I've had reports of the installer not initializing the data cluster, which results in Postgres not starting. It seems to be random, and I haven't figured out the cause yet. If Postgres won't start (you get an error "could not connect to server: No such file or directory" when trying to connect with psql), try manually initializing the cluster with:
/usr/local/pgsql-9.1/bin/initdb -U postgres \
-D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US"
Or see the Locales and Encodings readme if you need a different locale or encoding.
Then stop and start Postgres as specified in the read me.

Yeah, I had read that somewhere too, although in my disorientation over the last couple of hours didn't find it anymore. But I did try it out, but got a

"initdb: could not access directory "/usr/local/pgsql-9.1/data": Permission denied"

I guess this is solvable with some "su" access or so. But no idea how. The data directory looks like this:

drwx------ 18 _postgres _postgres 612 Jun 14 14:25 data

So, the user is not anymore "postgres", but "_postgres", right? I read that this changed with Lion, but not sure how this applied to use with Kyngchaos libraries.

Thanks a lot for your help!

On 06/14/2012 06:48 AM, Stefan Schwarzer wrote:

Hi there,

I guess this is a typical user error. I searched around to find the solution, but in vain.

I just upgraded to Lion, and used Kyngchaos libraries for installation of Postgres.

Try to get running postgres, and I get this:

/usr/local/pgsql-9.1/bin/psql -U postgres
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/tmp/.s.PGSQL.5432"?

In my limited understanding, it seems that Postgres is not running. When I use:

ps auxw | grep post

out comes only the "grep post", but no postgres process.

When I use:

sudo launchctl load /Library/LaunchDaemons/org.postgresql.postgres.plist

it says:

org.postgresql.postgres: Already loaded

and displays in the "ps" list then:

user 935 0.0 0.1 2493888 7296 ?? Ss 3:24PM 0:00.12 /System/Library/PrivateFrameworks/DiskImages.framework/Resources/diskimages-helper -uuid 9EFB9424-7971-4A8B-9D73-B93BD7F1DB5F -post-exec 4

(which looks a bit strange to me (DiskImages ??))

I am somewhat lost (and worse is that it worked the other day, before re-installing Lion anew.).

http://www.kyngchaos.com/software/postgres
"
Notes

NOTE: I've had reports of the installer not initializing the data cluster, which results in Postgres not starting. It seems to be random, and I haven't figured out the cause yet. If Postgres won't start (you get an error "could not connect to server: No such file or directory" when trying to connect with psql), try manually initializing the cluster with:
/usr/local/pgsql-9.1/bin/initdb -U postgres \
-D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US"
Or see the Locales and Encodings readme if you need a different locale or encoding.
Then stop and start Postgres as specified in the read me.

Yeah, I had read that somewhere too, although in my disorientation over the last couple of hours didn't find it anymore. But I did try it out, but got a

"initdb: could not access directory "/usr/local/pgsql-9.1/data": Permission denied"

I guess this is solvable with some "su" access or so. But no idea how. The data directory looks like this:

drwx------ 18 _postgres _postgres 612 Jun 14 14:25 data

So, the user is not anymore "postgres", but "_postgres", right? I read that this changed with Lion, but not sure how this applied to use with Kyngchaos libraries.

I am not an Apple user so all I can do now is point you at the below. Answer 1 would seem to be a solution:

http://stackoverflow.com/questions/6814127/lion-update-removed-the-postgres-user-how-to-restore-it

Thanks a lot for your help!

--
Adrian Klaver
adrian.klaver@gmail.com

I guess this is a typical user error. I searched around to find the solution, but in vain.

I just upgraded to Lion, and used Kyngchaos libraries for installation of Postgres.

Try to get running postgres, and I get this:

/usr/local/pgsql-9.1/bin/psql -U postgres
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/tmp/.s.PGSQL.5432"?

In my limited understanding, it seems that Postgres is not running. When I use:

ps auxw | grep post

out comes only the "grep post", but no postgres process.

When I use:

sudo launchctl load /Library/LaunchDaemons/org.postgresql.postgres.plist

it says:

org.postgresql.postgres: Already loaded

and displays in the "ps" list then:

user 935 0.0 0.1 2493888 7296 ?? Ss 3:24PM 0:00.12 /System/Library/PrivateFrameworks/DiskImages.framework/Resources/diskimages-helper -uuid 9EFB9424-7971-4A8B-9D73-B93BD7F1DB5F -post-exec 4

(which looks a bit strange to me (DiskImages ??))

I am somewhat lost (and worse is that it worked the other day, before re-installing Lion anew.).

I need unfortunately to come back to this issue. I (again) re-installed Lion from scratch, and finally got everything working. The Postgres was running, I uploaded a couple of dumped SQL files. And then re-started the machine for another reason. And suddenly it says again the it can't connect to the server.

I tried
/usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US

and
/usr/local/pgsql-9.1/bin/pg_ctl -D /usr/local/pgsql-9.1/data/ -l logfile start

and
sudo launchctl load /Library/LaunchDaemons/org.postgresql.postgres.plist

… but nothing happens. I don't have the feeling that it's a problem with the "postgres" and "_postgres" users (as it has worked before already).

Can anyone give me a hint how I can figure out where the problem lies and what I can do about it? Why did it work before I restarted the computer and why does it not work anymore?

Thanks a lot for any hints!

On 06/19/2012 01:32 AM, Stefan Schwarzer wrote:

I need unfortunately to come back to this issue. I (again) re-installed Lion from scratch, and finally got everything working. The Postgres was running, I uploaded a couple of dumped SQL files. And then re-started the machine for another reason. And suddenly it says again the it can't connect to the server.

I tried
/usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US

and
/usr/local/pgsql-9.1/bin/pg_ctl -D /usr/local/pgsql-9.1/data/ -l logfile start

and
sudo launchctl load /Library/LaunchDaemons/org.postgresql.postgres.plist

� but nothing happens. I don't have the feeling that it's a problem with the "postgres" and "_postgres" users (as it has worked before already).

Can anyone give me a hint how I can figure out where the problem lies and what I can do about it? Why did it work before I restarted the computer and why does it not work anymore?

Thanks a lot for any hints!

When troubleshooting I am firm believer in working from the known to the
unknown. In that vein:

1) Is there /usr/local/pgsql-9.1/data/?

a) If so are there subdirectories in it indicating cluster was
created? i.e. base/ global/ pg_clog/, etc
b) If not is there a Postgres data directory anywhere on machine?

2) When you say nothing happens does that mean nothing is written to log
file and/or terminal? No process shows up in process list?

3) If something does happen in, terms of error messages, what are they?

4) Have you looked at system (not Postgres specific) logs to see if this
a system issue?

5) What user are you running the above commands as?
a) What user is associated with the Postgres data directory(if it
exists)?

--
Adrian Klaver
adrian.klaver@gmail.com

I need unfortunately to come back to this issue. I (again) re-installed Lion from scratch, and finally got everything working. The Postgres was running, I uploaded a couple of dumped SQL files. And then re-started the machine for another reason. And suddenly it says again the it can't connect to the server.

I tried
/usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US

and
/usr/local/pgsql-9.1/bin/pg_ctl -D /usr/local/pgsql-9.1/data/ -l logfile start

and
sudo launchctl load /Library/LaunchDaemons/org.postgresql.postgres.plist

… but nothing happens. I don't have the feeling that it's a problem with the "postgres" and "_postgres" users (as it has worked before already).

Can anyone give me a hint how I can figure out where the problem lies and what I can do about it? Why did it work before I restarted the computer and why does it not work anymore?

Thanks a lot for any hints!

When troubleshooting I am firm believer in working from the known to the unknown. In that vein:

1) Is there /usr/local/pgsql-9.1/data/?

Yes:

drwx------ 18 _postgres _postgres 612 Jun 19 09:41 data

a) If so are there subdirectories in it indicating cluster was created? i.e. base/ global/ pg_clog/, etc

Yes:

drwx------ 7 _postgres _postgres 238 Jun 19 08:59 base
drwx------ 43 _postgres _postgres 1462 Jun 19 09:41 global
….

2) When you say nothing happens does that mean nothing is written to log file and/or terminal? No process shows up in process list?

When I do: sudo launchctl load /Library/LaunchDaemons/org.postgresql.postgres.plist
it says: org.postgresql.postgres: Already loaded

When I do: /usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US
it says: The files belonging to this database system will be owned by user "xxx".
This user must also own the server process.
The database cluster will be initialized with locale en_US.
The default text search configuration will be set to "english".
initdb: could not access directory "/usr/local/pgsql-9.1/data": Permission denied

Same when using "_postgres" instead of "postgres".

When I do: sudo su - _postgres /usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US
it seems to run, but still, same error message "psql: could not connect…."

And still nothing in the process list (using "ps auxw | grep post").

3) If something does happen in, terms of error messages, what are they?

4) Have you looked at system (not Postgres specific) logs to see if this a system issue?

I looked at Apple's Console, where all (?) logs/messages are being assembled, but nothing worrisome there. is there any other specific place where I can look for error messages?

5) What user are you running the above commands as?

I am user with "Administrator" rights.

a) What user is associated with the Postgres data directory(if it exists)?

See above, "_postgres". There is or could be confusion between Apple's "_postgres" and the normal "postgres" user. But it looks as it isn't in this case..

Thanks for your help!

On 06/20/2012 10:40 PM, Stefan Schwarzer wrote:

I need unfortunately to come back to this issue. I (again) re-installed Lion from scratch, and finally got everything working. The Postgres was running, I uploaded a couple of dumped SQL files. And then re-started the machine for another reason. And suddenly it says again the it can't connect to the server.

I tried
/usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US

and
/usr/local/pgsql-9.1/bin/pg_ctl -D /usr/local/pgsql-9.1/data/ -l logfile start

and
sudo launchctl load /Library/LaunchDaemons/org.postgresql.postgres.plist

� but nothing happens. I don't have the feeling that it's a problem with the "postgres" and "_postgres" users (as it has worked before already).

Can anyone give me a hint how I can figure out where the problem lies and what I can do about it? Why did it work before I restarted the computer and why does it not work anymore?

Thanks a lot for any hints!

When troubleshooting I am firm believer in working from the known to the unknown. In that vein:

1) Is there /usr/local/pgsql-9.1/data/?

Yes:

drwx------ 18 _postgres _postgres 612 Jun 19 09:41 data

a) If so are there subdirectories in it indicating cluster was created? i.e. base/ global/ pg_clog/, etc

Yes:

drwx------ 7 _postgres _postgres 238 Jun 19 08:59 base
drwx------ 43 _postgres _postgres 1462 Jun 19 09:41 global
�.

2) When you say nothing happens does that mean nothing is written to log file and/or terminal? No process shows up in process list?

When I do: sudo launchctl load /Library/LaunchDaemons/org.postgresql.postgres.plist
it says: org.postgresql.postgres: Already loaded

When I do: /usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US
it says: The files belonging to this database system will be owned by user "xxx".
This user must also own the server process.
The database cluster will be initialized with locale en_US.
The default text search configuration will be set to "english".
initdb: could not access directory "/usr/local/pgsql-9.1/data": Permission denied

So at a guess user 'xxx' is not '_postgres'. You need to be the
_postgres user when doing the initdb.

Same when using "_postgres" instead of "postgres".

When I do: sudo su - _postgres /usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US
it seems to run, but still, same error message "psql: could not connect�."

See, here the initdb worked. Doing the inidtdb is not the same as
starting the database. initdb only creates the initial database cluster.

To start the database you need to do something like(as _postgres):

/usr/local/pgsql-9.1/bin/pg_ctl start -D /usr/local/pgsql-9.1/data

And still nothing in the process list (using "ps auxw | grep post").

3) If something does happen in, terms of error messages, what are they?

4) Have you looked at system (not Postgres specific) logs to see if this a system issue?

I looked at Apple's Console, where all (?) logs/messages are being assembled, but nothing worrisome there. is there any other specific place where I can look for error messages?

5) What user are you running the above commands as?

I am user with "Administrator" rights.

The commands need to be run as the _postgres user. Postgres will not run
as root.

a) What user is associated with the Postgres data directory(if it exists)?

See above, "_postgres". There is or could be confusion between Apple's "_postgres" and the normal "postgres" user. But it looks as it isn't in this case..

Thanks for your help!

--
Adrian Klaver
adrian.klaver@gmail.com

When I do: sudo launchctl load /Library/LaunchDaemons/org.postgresql.postgres.plist
it says: org.postgresql.postgres: Already loaded

When I do: /usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US
it says: The files belonging to this database system will be owned by user "xxx".
This user must also own the server process.
The database cluster will be initialized with locale en_US.
The default text search configuration will be set to "english".
initdb: could not access directory "/usr/local/pgsql-9.1/data": Permission denied

So at a guess user 'xxx' is not '_postgres'. You need to be the _postgres user when doing the initdb.

Same when using "_postgres" instead of "postgres".

When I do: sudo su - _postgres /usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US
it seems to run, but still, same error message "psql: could not connect…."

See, here the initdb worked. Doing the inidtdb is not the same as starting the database. initdb only creates the initial database cluster.

To start the database you need to do something like(as _postgres):

/usr/local/pgsql-9.1/bin/pg_ctl start -D /usr/local/pgsql-9.1/data

Thanks so much for those tips. If I understand it correctly, the commands should be then:

sudo su - _postgres /usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US
sudo su - _postgres /usr/local/pgsql-9.1/bin/pg_ctl start -D /usr/local/pgsql-9.1/data

Although I don't get an error message, I don't have the feeling that it started the server. There is still nothing in the process list, and a normal "psql" results in the same message as before "psql: could not connect…"

So sorry for bothering you guys… just being really frustrated now…

If you have any ideas, please let me know… :-)

Stef

sudo su - _postgres /usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US
sudo su - _postgres /usr/local/pgsql-9.1/bin/pg_ctl start -D /usr/local/pgsql-9.1/data

Although I don't get an error message, I don't have the feeling that it started the server. There is still nothing in the process list, and a normal "psql" results in the same message as before "psql: could not connect…"

So sorry for bothering you guys… just being really frustrated now…

If you have any ideas, please let me know… :-)

I just went back to the postgres documentation [1]http://www.postgresql.org/docs/9.1/static/server-start.html (actually reading all google results on the error message one after the other) and tried out what was said there (adapted to my conditions):

sudo -u _postgres /usr/local/pgsql-9.1/bin/postgres -D /usr/local/pgsql-9.1/data

and suddenly postgres runs….

[1]: http://www.postgresql.org/docs/9.1/static/server-start.html

On 06/22/2012 03:19 PM, Stefan Schwarzer wrote:

sudo su - _postgres /usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US
sudo su - _postgres /usr/local/pgsql-9.1/bin/pg_ctl start -D /usr/local/pgsql-9.1/data

Although I don't get an error message, I don't have the feeling that it started the server. There is still nothing in the process list, and a normal "psql" results in the same message as before "psql: could not connect�"

So sorry for bothering you guys� just being really frustrated now�

If you have any ideas, please let me know� :-)

I just went back to the postgres documentation [1] (actually reading all google results on the error message one after the other) and tried out what was said there (adapted to my conditions):

sudo -u _postgres /usr/local/pgsql-9.1/bin/postgres -D /usr/local/pgsql-9.1/data

and suddenly postgres runs�.

You really should be able to use pg_ctl though.

I'm puzzled about why you don't appear to be looking at the server error
logs (/usr/local/pgsql-9.1/data/pg_log) during troubleshooting. They're
your main source of info.

--
Craig Ringer

sudo su - _postgres /usr/local/pgsql-9.1/bin/initdb -U postgres -D /usr/local/pgsql-9.1/data --encoding=UTF8 --locale=en_US
sudo su - _postgres /usr/local/pgsql-9.1/bin/pg_ctl start -D /usr/local/pgsql-9.1/data

Although I don't get an error message, I don't have the feeling that it started the server. There is still nothing in the process list, and a normal "psql" results in the same message as before "psql: could not connect…"

So sorry for bothering you guys… just being really frustrated now…

If you have any ideas, please let me know… :-)

I just went back to the postgres documentation [1] (actually reading all google results on the error message one after the other) and tried out what was said there (adapted to my conditions):

sudo -u _postgres /usr/local/pgsql-9.1/bin/postgres -D /usr/local/pgsql-9.1/data

and suddenly postgres runs….

You really should be able to use pg_ctl though.

I'm puzzled about why you don't appear to be looking at the server error logs (/usr/local/pgsql-9.1/data/pg_log) during troubleshooting. They're your main source of info.

Hmm, I guess it's because I didn't think of it, I was't really aware of it (although I tried to use the Console Error Messages to find any errors), and wouldn't have been sure how to access it (as it belongs to the _postgres user). But then, it doesn't exist. I see pg_clog and pg_xlog...

On 06/25/2012 02:50 PM, Stefan Schwarzer wrote:

Craig Ringer wrote:

I'm puzzled about why you don't appear to be looking at the server error logs (/usr/local/pgsql-9.1/data/pg_log) during troubleshooting. They're your main source of info.

Hmm, I guess it's because I didn't think of it, I was't really aware of it (although I tried to use the Console Error Messages to find any errors), and wouldn't have been sure how to access it (as it belongs to the _postgres user). But then, it doesn't exist. I see pg_clog and pg_xlog...

Perhaps your install places it somewhere else. Sorry, I don't really do
mac. The PostgreSQL log directory can be found by examining
postgresql.conf in the data directory. The 'log_directory' parameter
specifies where Pg writes its logs to.

--
Craig Ringer

I just went back to the postgres documentation [1] (actually reading all google results on the error message one after the other) and tried out what was said there (adapted to my conditions):

sudo -u _postgres /usr/local/pgsql-9.1/bin/postgres -D /usr/local/pgsql-9.1/data

and suddenly postgres runs….

And for whatever reason, after having worked this morning, it doesn't work anymore after I restarted the computer in the middle of the day. I can't believe it.

When I type in:

sudo -u _postgres /usr/local/pgsql-9.1/bin/postgres -D /usr/local/pgsql-9.1/data

it spits out:

LOG: 00000: could not identify current directory: Permission denied
LOCATION: find_my_exec, exec.c:126
FATAL: XX000: /usr/local/pgsql-9.1/bin/postgres: could not locate my own executable path
LOCATION: getInstallationPaths, postmaster.c:1138

I looked around, but couldn't find a plausible explanation for this.

On 06/25/2012 04:21 PM, Stefan Schwarzer wrote:

I just went back to the postgres documentation [1] (actually reading all google results on the error message one after the other) and tried out what was said there (adapted to my conditions):

sudo -u _postgres /usr/local/pgsql-9.1/bin/postgres -D /usr/local/pgsql-9.1/data

and suddenly postgres runs�.

And for whatever reason, after having worked this morning, it doesn't work anymore after I restarted the computer in the middle of the day. I can't believe it.

When I type in:

sudo -u _postgres /usr/local/pgsql-9.1/bin/postgres -D /usr/local/pgsql-9.1/data

it spits out:

LOG: 00000: could not identify current directory: Permission denied

'cd' to the postgresql datadir before running the command, or use pg_ctl
instead of trying to launch the postgres server executable directly.

It's trying to get information on the current directory - probably your
home dir - but the _postgres user doesn't have access to it.

--
Craig Ringer

Craig Ringer <ringerc@ringerc.id.au> writes:

On 06/25/2012 04:21 PM, Stefan Schwarzer wrote:

When I type in:

sudo -u _postgres /usr/local/pgsql-9.1/bin/postgres -D /usr/local/pgsql-9.1/data

it spits out:

LOG: 00000: could not identify current directory: Permission denied

It's trying to get information on the current directory - probably your
home dir - but the _postgres user doesn't have access to it.

Try adding the "-i" option to the sudo command. Starting postgres
under whatever environment you happen to have in your interactive shell
isn't a very good idea anyway --- things will be more predictable with
user _postgres' login environment.

regards, tom lane