Postgresql dump permission denied

I get this error while trying to dump database, i entered

linuxuser $ sudo su postgres
linuxuser $ [sudo] password for linuxuser:...
$ pg_dump -h localhost mydb >tempfile
$ sh: cannot create tempfile: Permission denied

What the problem? i've just installed fresh postgresql.

Write into directory where postgres user has write access. For instance /tmp.

$ pg_dump -h localhost mydb >/tmp/tempfile

In your attempt postgres user tries to create a file in some random directory belonging to the other user.

backup and restore can be done by any unpriviledged user that knows the postgres superuser password by changing permissions on the working directory:

% mkdir backup

% chmod 0777 backup

% su postgres

[enter password]

$ cd backup

$ pg_dump mydb >tempfile

$ exit

"tempfile" will be owned by postgres and same group as the user

sudo su postgres doesn't change the current directory so you're still in linuxuser's home directory and postgres has no permission to write into it. Change to a different directory