Thread: pg_dump backup problems with password authentication

Hi all,


I am using PostgreSQL 7.0.2 in RedHat Linux 6.2

I have changed the default authentication, in the pg_hba.conf
file, from trust to password.

Unfortunately, this is giving me problems with pg_dump

I am trying to do a copy of just one database (with all its
tables, primary and foreign keys, check clauses, triggers, etc).

So, I followed the instructions at:
http://postgresql.rmplc.co.uk/users-lounge/docs/7.0/admin/manage-ag1655.htm

and did a pg_dump dbname > dbname.pgdump
(I replaced dbname by my database name, obviously)


Because I have password authentication set, I get an
error message:

Connection to database 'dbname' failed.
fe_sendauth: no password supplied

So, I did a man pg_dump and found out that -u would prompt
for username and password, and -v would give a verbose output.
And so I did:
pg_dump -u -v dbname > dbname.pgdump


The problem is when I press the ENTER key on that command:
it just sits there! Eventually, I have to hit CTRL+C to get out.


Can any kind soul explain me what I am doing wrong?  :(


Thanks in advance,
Ricardo Dias Marques
ricmarques@spamcop.net

On Thu, Dec 07, 2000 at 01:07:17PM +0000, Ricardo Dias Marques wrote:

> So, I did a man pg_dump and found out that -u would prompt
> for username and password, and -v would give a verbose output.
> And so I did:
> pg_dump -u -v dbname > dbname.pgdump
>
>
> The problem is when I press the ENTER key on that command:
> it just sits there! Eventually, I have to hit CTRL+C to get out.
>
>
> Can any kind soul explain me what I am doing wrong?  :(

Unfortunately, the prompts for your username and password come out
on standard output, which you're redirecting to the file. So you
don't see them. But pg_dump is listening; type in your username and
password as if you *had* seen the prompts and it will all work.
Alternatively, you can use "echo" to give them:

echo -n -e "username\npassword\n" | pg_dump -u -v dbname > dbname.pgdump

This is insecure, as your password is briefly visible in a full ps output,
but it works non-interactively, so you can do it in scripts (e.g., from
cron). Of course, that's potentially even more insecure...

Richard

Hi again,

I would like to thank Vasileiadis Spyros, Michael Ansley and
Richard Poole who all pointed out the nature of the problem
and the correct solution.


SUMMARY

The original situation was this:
1) I had changed authentication in pg_hba.conf from trust to
password
2) This gave me a problem with pg_dump
When I ran the command:
pg_dump -D -u -v databasename > database.sql
I didnt't get an Username prompt (the -u switch would do that)

The explanation for this was that the Username prompt appears
in stdout (STanDard OUTput), which *usually* is the screen,
but because I was redirecting output to a file, the Username:
prompt was being saved in the output file (database.sql)

The solution was to write the pg_dump command above, press
ENTER, and then write the username (the Username prompt doesn't
appear, as explained above), press ENTER, write the password
and press ENTER again. Using the -v switch, some lines appear
which show the operations being done (e.g., "reading
user-defined types", "finding Triggers for relation:", etc)

To restore the data, I edited the database.sql with joe
(I found out that my default configuration of pico was
breaking the lines at wrap points). I removed the Username,
and Password lines, and the \connect - postgres line. Then
I wrote the password in the first line (I didn't need to
write the Username, because I was logged in as user
postgres)

Then, I created the new database:
createdb newdatabase

And typed the restore command:
psql newdatabase < database.sql

Et voilá!  :)


Thanks for all the help, and I hope this summary will be
useful to other people with the same problem (let me live
in my illusion that I'm not the only one, OK?  ;-)


Best wishes,
Ricardo Dias Marques
ricmarques@spamcop.net