For PostgreSQL 8.3 installations on Ubuntu, the default server log location is typically:

/var/log/postgresql/postgresql-8.3-main.log

This path follows the standard Ubuntu/Debian convention for PostgreSQL log files. The exact filename might vary slightly depending on your cluster name, but will generally follow the pattern postgresql-{version}-{cluster}.log.

If you can't locate the logs in the default location, try these methods:

# Check PostgreSQL configuration
grep log_directory /etc/postgresql/8.3/main/postgresql.conf
grep log_filename /etc/postgresql/8.3/main/postgresql.conf

# Search the filesystem for likely locations
sudo find /var/log -name "*postgres*" -type f
sudo find / -name "pg_log" -type d 2>/dev/null

To modify log settings in PostgreSQL 8.3, edit the configuration file:

sudo nano /etc/postgresql/8.3/main/postgresql.conf

Key parameters to check or modify:

# Directory to store log files
log_directory = 'pg_log'

# Log file name pattern
log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'

# Log statement controls
log_statement = 'all'  # none, ddl, mod, all

For systems without logrotate already configured, you can add this to /etc/logrotate.d/postgresql-8.3:

/var/log/postgresql/postgresql-8.3-main.log {
    weekly
    missingok
    rotate 12
    compress
    delaycompress
    notifempty
    create 640 postgres adm
    sharedscripts
    postrotate
        /etc/init.d/postgresql reload >/dev/null
    endscript
}

Use these commands to monitor logs as they're written:

# Basic tail
sudo tail -f /var/log/postgresql/postgresql-8.3-main.log

# Tail with grep filtering
sudo tail -f /var/log/postgresql/postgresql-8.3-main.log | grep ERROR

# Use less for backward navigation
sudo less +F /var/log/postgresql/postgresql-8.3-main.log

If logs aren't appearing where expected:

1. Verify the PostgreSQL service is running: sudo service postgresql-8.3 status
2. Check for configuration errors: sudo -u postgres psql -c "SHOW log_directory;"
3. Ensure proper permissions: sudo chown postgres:adm /var/log/postgresql
4. Restart PostgreSQL after configuration changes: sudo service postgresql-8.3 restart

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For PostgreSQL 8.3 installations on Ubuntu, server logs are typically found in:

/var/log/postgresql/postgresql-8.3-main.log

This path follows the standard Ubuntu/Debian logging conventions. The filename may vary slightly depending on your cluster name (here "main" is the default cluster).

If logs aren't in the default location, check these configuration approaches:

1. Checking postgresql.conf

The primary configuration file usually contains logging directives:

# Connect to PostgreSQL
psql -U postgres

# Show config file location
SHOW config_file;

# Or check logging parameters
SHOW log_directory;
SHOW log_filename;

2. System Service Configuration

Ubuntu's init script may override logging locations. Check the service file:

cat /etc/init.d/postgresql-8.3 | grep log

Case 1: Custom Log Location

If you've specified a custom log_directory in postgresql.conf:

log_directory = '/var/log/pg_logs'
log_filename = 'postgresql-%Y-%m-%d.log'

You'll need to check the configured directory.

Case 2: Syslog Configuration

When using syslog (common in older versions):

# Check syslog configuration
grep postgres /etc/syslog.conf

# Or search system logs
grep postgres /var/log/syslog

Example 1: Rotating Logs

Add log rotation configuration in /etc/logrotate.d/postgresql-8.3:

/var/log/postgresql/postgresql-8.3-main.log {
    daily
    rotate 7
    compress
    delaycompress
    missingok
    notifempty
    create 640 postgres adm
    sharedscripts
    postrotate
        /etc/init.d/postgresql-8.3 reload > /dev/null
    endscript
}

Example 2: Increasing Log Verbosity

To debug issues, modify postgresql.conf:

log_min_messages = debug1
log_min_error_statement = debug1
log_connections = on
log_disconnections = on
log_statement = 'all'

Remember to reload the configuration after changes:

sudo /etc/init.d/postgresql-8.3 reload