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I have just installed postgres 8.4 on Ubuntu 9.10 and it has never asked me to create a superuser. Is there a default superuser and its password? If not, how do I create a new one?

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5 Answers 5

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CAUTION The answer about changing the UNIX password for "postgres" through "$ sudo passwd postgres" is not preferred, and can even be DANGEROUS!

This is why: By default, the UNIX account "postgres" is locked, which means it cannot be logged in using a password. If you use "sudo passwd postgres", the account is immediately unlocked. Worse, if you set the password to something weak, like "postgres", then you are exposed to a great security danger. For example, there are a number of bots out there trying the username/password combo "postgres/postgres" to log into your UNIX system.

What you should do is follow Chris James's answer:

sudo -u postgres psql postgres

# \password postgres

Enter new password: 

To explain it a little bit. There are usually two default ways to login to PostgreSQL server:

  1. By running the "psql" command as a UNIX user (so-called IDENT/PEER authentication), e.g.: sudo -u postgres psql. Note that sudo -u does NOT unlock the UNIX user.

  2. by TCP/IP connection using PostgreSQL's own managed username/password (so-called TCP authentication) (i.e., NOT the UNIX password).

So you never want to set the password for UNIX account "postgres". Leave it locked as it is by default.

Of course things can change if you configure it differently from the default setting. For example, one could sync the PostgreSQL password with UNIX password and only allow local logins. That would be beyond the scope of this question.

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  • 13
    so, how do you lock user postgres back?
    – ultrajohn
    Jul 4, 2012 at 4:30
  • 4
    @ultrajohn - depends on distribution you use, but you can edit /etc/passwd and put * instead of the password
    – lzap
    Sep 12, 2012 at 9:50
  • 3
    /etc/shadow is where the password is kept @lzap. Sep 20, 2012 at 18:56
  • 2
    Right, you can either set /sbin/nologin in /etc/passwd or put * instead of the password in /etc/shadow.
    – lzap
    Sep 21, 2012 at 9:37
  • 35
    passwd --lock postgres
    – Stéphane
    Jul 25, 2013 at 18:04
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Enter on the command line:

$ sudo -u postgres psql postgres
postgres=# \password postgres

You'll see:

Enter new password: 
Enter it again:
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  • 10
    This is what's needed to use a tool like pgadminIII (when setting up a server profile) immediately after Postgres itself is installed. Thanks!
    – limist
    Jul 10, 2011 at 16:55
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You manipulate postgres through the user postgres, as so:

# su - postgres
$ createdb mydb
$ psql -s mydb
# create user someuser password 'somepassword';
# GRANT ALL PRIVILEGES ON DATABASE mydb TO someuser;
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  • 5
    @ThierryLam You must be root to su to the postgres user without entering a password. On most systems the Postgres Unix account is locked (no password will work), which means only root may su to that account.
    – voretaq7
    Nov 7, 2013 at 22:59
  • 2
    Use sudo instead of su. Aug 8, 2014 at 13:30
  • 10
    I had to run sudo su - postgres :\ Oct 8, 2014 at 14:08
  • 3
    @Jim Schubert: you can also run sudo -u postgres. Nov 24, 2014 at 9:28
  • 2
    sudo -u postgres psql - works also so you can do it in one step.
    – Ominus
    Nov 20, 2017 at 13:35
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In Windows, do the following (IMPORTANT: Use a Windows administrator account):

  1. After installation, open <PostgreSQL PATH>\data\pg_hba.conf.

  2. Modify these two lines, and change "md5" to "trust":

    host all all 127.0.0.1/32 md5

    host all all ::1/128 md5

  3. Restart the PostgreSQL service (might not be necessary).

  4. (Optional) Open a command prompt, and change code page to 1252:

    cmd.exe /c chcp 1252

  5. Log in to PostgreSQL. Non password will be needed (notice the uppercase -U parameter):

    psql -U postgres

  6. (Optional, recommended for security reasons) Change the postgres user's password:

    \password postgres

    and change "trust" back to "md5" in pg_hba.conf.

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If you are trying to access the PostgreSQL shell, you can type:

psql -U postgres my_database

Where my_database is your database name.

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