When installing PostgreSQL 8.4 via Ubuntu's repositories, the configuration files follow Debian's unique directory structure:

/etc/postgresql/8.4/main/postgresql.conf
/etc/postgresql/8.4/main/pg_hba.conf

To programmatically locate these files, you can query PostgreSQL directly:

psql -U postgres -c "SHOW config_file;"
psql -U postgres -c "SHOW hba_file;"

Or use find command:

sudo find / -name postgresql.conf 2>/dev/null
sudo find / -name pg_hba.conf 2>/dev/null

In non-Debian systems or custom installations, check these locations:

• /var/lib/postgresql/data/
• /usr/local/pgsql/data/
• $PGDATA/ (if PGDATA environment variable is set)

Typical permissions for these sensitive files:

-rw-r----- 1 postgres postgres 20000 Mar 15 12:34 postgresql.conf
-rw------- 1 postgres postgres  4512 Mar 15 12:34 pg_hba.conf

For deployment scripts, consider this Bash function:

check_pg_configs() {
    local pg_version=${1:-8.4}
    local conf_dir="/etc/postgresql/${pg_version}/main"
    
    if [[ ! -f "${conf_dir}/postgresql.conf" ]]; then
        echo "ERROR: postgresql.conf not found in ${conf_dir}" >&2
        return 1
    fi
    
    if [[ ! -f "${conf_dir}/pg_hba.conf" ]]; then
        echo "ERROR: pg_hba.conf not found in ${conf_dir}" >&2
        return 1
    fi
    
    echo "Configuration files verified in ${conf_dir}"
    return 0
}

After modifying these files, reload the configuration:

# For Ubuntu's init system:
sudo /etc/init.d/postgresql-8.4 reload

# Alternative methods:
sudo service postgresql-8.4 reload
sudo -u postgres pg_ctlcluster 8.4 main reload

For PostgreSQL 8.4 installed via Ubuntu's repositories, the configuration files are typically found in:

/etc/postgresql/8.4/main/postgresql.conf
/etc/postgresql/8.4/main/pg_hba.conf

If you're unsure about the exact location, try these PostgreSQL commands:

-- Connect to PostgreSQL and run:
SHOW config_file;
SHOW hba_file;

Or use Linux find command:

sudo find / -name "postgresql.conf" 2>/dev/null
sudo find / -name "pg_hba.conf" 2>/dev/null

Ubuntu's PostgreSQL package maintains version-specific configuration directories. The pattern is:

/etc/postgresql/{version}/main/

Where {version} corresponds to your PostgreSQL version (8.4 in this case).

After modifying these files, remember to reload PostgreSQL:

sudo /etc/init.d/postgresql-8.4 reload
# Or alternatively:
sudo service postgresql reload

Best practice suggests creating backups before editing:

sudo cp /etc/postgresql/8.4/main/postgresql.conf /etc/postgresql/8.4/main/postgresql.conf.bak
sudo cp /etc/postgresql/8.4/main/pg_hba.conf /etc/postgresql/8.4/main/pg_hba.conf.bak

If you're running multiple PostgreSQL clusters, each will have its own configuration directory under:

/etc/postgresql/8.4/{cluster-name}/

Use pg_lsclusters to list all available clusters.

For this older version, some configuration parameters may differ from newer releases. Always check the version-specific documentation.