Regarding the definition of Postgresql port 5432:
Port 5432 has been registered with IANA (The Internet Assigned Numbers Authority),
And assign this port uniquely to Postgres.
This means that a server with Linux OS installed will have this reserved port even if the postgresql database has not been installed.
The method to view this reserved port is as follows:
new@newdb-> cat /etc/services |grep 5432 postgres 5432/tcp postgresql # POSTGRES postgres 5432/udp postgresql # POSTGRES
The /etc/services file contains the mapping between the service name and the port number, and many system programs need to use this file.
Generally speaking, do not modify the contents of the file, because these settings are Internet-standard settings.
Once modified, it may cause system conflicts and prevent users from accessing resources normally.
Supplement: PostgreSQL command interface
The psql client program provides a command line interface to the PostgreSQL server. It uses command line parameters to control the functions enabled in the client interface.
The administrator account name of PostgreSQL is postgres. Because PostgreSQL uses a Linux user account to verify users, you must log in as a Linux account postgres to access the PostgreSQL server as a postgres user.
Because the postgres user account is a special account, it should not be assigned a password. This way no one can break into the system using the postgres account.
If you want to log in with your postgres account, you must be the root account and then use the su command to change it to the postgres user.
There are two types of commands that psql programs can use:
Standard SQL statements
PostgreSQL metacommand
Commonly used PostgreSQL metacommands:
\lList available databases
\cConnect to a database
\dtList tables in a database
\duList PostgreSQL users
\zList table permissions
\?List all available metacommands
\hList all available SQL commands
\qExit the database
PostgreSQL user accounts are different from accounts in MySQL. The login account in PostgreSQL is called the login role. The PostgreSQL server matches the login role with the Linux system user account.
The above is personal experience. I hope you can give you a reference and I hope you can support me more. If there are any mistakes or no complete considerations, I would like to give you advice.